Why Republicans start out as favorites in the 2026 Senate elections

In politics, timing can be everything. While the 2026 midterm elections are still two years away, we can already say that Republicans' position in the race for the U.S. Senate exemplifies this maxim. Although midterms tend to be rough for the president's party, the GOP starts as favorites to retain the majority they just won in the Senate, thanks to how that timing interacts with the chamber's current partisan makeup and its underlying fundamental structures, which are hardwired in a way that currently boosts Republicans.

Part of that hardwiring can be found in Article I, Section 3 of the Constitution, which calls for the Senate to be divided into three groups of seats (known as classes) that each serve staggered six-year terms, such that only about one-third of the chamber's seats are up for reelection every two years. As a result, in our highly partisan era, the set of seats that happen to be on the ballot in a given year can matter almost as much to each party's prospects of winning a majority as the overall electoral environment. By contrast, the U.S. House of Representatives is more at the mercy of national electoral conditions because all 435 seats are up in each election.

In November 2026, we will likely see at least 35 Senate seats up for election: 33 seats in Class II, a special election in Ohio for Vice President-elect JD Vance's seat and another likely special election in Florida for the seat currently held by Sen. Marco Rubio, whom President-elect Donald Trump has nominated to become secretary of state. Depending on other events, additional special elections could also occur.

The Senate map favors the GOP

Heading into 2026, Republicans have about as favorable of a Senate map as they could hope for under the circumstances. This is true despite the fact that the incoming presidential party must defend 22 of the 35 seats that will likely be up for election (including Vance's and Rubio's seats). Strikingly, though, only one of those 22 Republican-held seats — held by Sen. Susan Collins of Maine — is in a state that outgoing Vice President Kamala Harris carried in the 2024 presidential election. The other 21 seats are all in states that Trump won. In contrast, Democrats will be defending just 13 seats overall, but two of them are in states that Trump won this year.

This is important because most voters these days back the same party for president and Senate, so each party's target list of seats begins with any seats held by the opposition in states that the party carried in the last presidential election, and then any other seats that were relatively competitive. Looking ahead to 2026, the Democrats are expected to go into the election holding 47 Senate seats (including two held by independents who caucus with them), so they would need to flip four seats to win a majority — while also defending their seats in Trump-won Michigan and Georgia. With just one Republican seat expected to come up in a state Trump lost, this map doesn't give Democrats many obvious opportunities.

Now, this is not to say that Democrats have no chance of winning back the Senate in 2026 — just that they need some combination of a very favorable electoral environment, a sizable swing back in their direction from the 2024 presidential cycle and/or a shift in the party coalitions. More often than not, the president's party does indeed lose Senate seats in midterms: In 13 of 20 midterms since World War II, the party in the White House has lost at least one seat.

But the degree of difficulty Democrats face in 2026 is unusually high because Republicans are defending just about the fewest clearly vulnerable seats that any president's party has had to defend in a recent midterm. Beyond Collins's seat, only one other Republican seat up in 2026 is in a state that Trump won by fewer than 10 percentage points against Harris: North Carolina, which Trump carried by about 3 points and where Republican Sen. Thom Tillis is seeking reelection.

The number of vulnerable seats for a president's party has been a crucial factor in past midterms' Senate results. For instance, Democrats faced a particularly tough map in 2014, when they had to defend seven seats that then-President Barack Obama had lost in 2012; they lost all seven of those, plus two others for a net loss of nine. Conversely, Democrats went into 2022 in much better shape because they didn't have to defend a single seat in a state that President Joe Biden lost; that likely helped them avoid a midterm loss, as they wound up gaining one seat in Republican-held Pennsylvania.

In the next Congress, Collins will be the only GOP senator out of 53 in total who represents a state that Harris won. Across all presidential and midterm cycles over the past four decades, this represents the most Senate seats a party has held in states won by their presidential nominee in the last presidential election. (The previous record involved Trump, too, when the GOP headed into the 2020 presidential election holding 51 seats in states he'd carried in 2016.)

These circumstances also get at Republicans' larger structural edge: Each state gets two seats in the Senate, but these days, there are consistently more red-leaning states than blue-leaning states relative to the country as a whole. For example, 29 states leaned redder at the presidential level than the national popular vote in 2024, while 31 did so in 2020 and 32 in 2016. That means Republicans now hold more Senate seats in comfortably red territory than they ever have, while Democrats have relied on "crossover" seats in red-leaning states to hold onto majorities in recent years. Even after losing a few of these critical seats in 2024 (in West Virginia, Montana and Ohio), Democrats currently hold 10 seats in states won by Trump, and they would need to once again win in hostile territory to retake the majority in 2026.

Democrats' difficult climb to regain a majority

For Democrats, then, the list of seats that they have a realistic chance of flipping is pretty short after Maine and North Carolina. To make further inroads — and have any shot at picking up the four seats they need — Democrats' best path likely involves winning some of the five seats expected to be on the ballot that are in states Trump carried by 10 to 15 points.

While it would not be historically out of the question for Democrats to win seats that are this red, it would rank as unusual compared with recent midterms. In the past three midterms, the most unfavorable seat that a non-presidential party has flipped was the GOP's 2014 victory in Iowa, which Obama carried by nearly 6 points in 2012 (Republicans that year also flipped Colorado, which Obama had won by slightly more than 5 points). We have to go back even further to find a seat flip to the non-presidential party after its state was truly uncompetitive in the preceding presidential election; in the 2010 midterms, the GOP won Obama's old seat in Illinois even after he'd won the state by 25 points in 2008.

It's certainly very early to break down the races in these seven states. After all, we don't know just who will run in any of them, whom Republican Gov. Mike DeWine might appoint to Vance's seat in Ohio, or whether Florida will definitely have a special election — as the Senate will need to confirm Rubio as secretary of state before his seat officially opens up. But let's take a quick look at what we know so far.

In Maine, Collins has said she plans to run for her sixth term in 2026. However, she's never had to run in a tough midterm environment for her party — her only previous midterm under a Republican president came in the 2002 cycle, which was an unusually good one for the GOP because then-President George W. Bush held a very high approval rating following the Sept. 11 attacks. Additionally, Collins has never had a primary challenger, but that could change if she upsets Trump and the party base — the moderate will be looking to strategically break with Trump this cycle to shore up her reelection chances. That said, there's also a good chance that one of her strongest potential general election opponents won't run against her: Democratic Rep. Jared Golden has managed to regularly win a red-leaning, rural seat in Maine, but he once worked for Collins and might instead campaign for the state's open gubernatorial seat.

North Carolina, meanwhile, has truly been a "close, but no cigar" state for Democrats in recent federal elections. The party has suffered narrow losses for president and/or Senate in 2012, 2014, 2016, 2020, 2022 and now 2024. But Tillis, who first won this seat in the red wave midterm of 2014, will have to walk a fine line by showing enough independence from Trump while not overly upsetting the GOP's right flank and provoking a serious primary challenge. Already viewed as suspect by many conservatives, Tillis is probably more in danger than Collins of having to contend with a notable primary opponent. As for Democrats, the biggest name floating around is outgoing Gov. Roy Cooper, although outgoing Rep. Wiley Nickel has already filed for the race.

The upcoming special election in Ohio will remain murky for some time, especially until we know who will take Vance's place. DeWine is far from a MAGA Republican, and he could choose a more traditional conservative who'll campaign to retain the seat in 2026. However, such an appointee would almost certainly have to contend with a major primary challenge in a state that has an incredibly deep bench of Republican officeholders. For Democrats, Sen. Sherrod Brown just lost his seat in Ohio earlier this month, but he hasn't ruled out the idea of running in 2026. Neither has former Rep. Tim Ryan, who lost to Vance in the state's 2022 Senate contest.

Florida's situation is even fuzzier. The state has raced to the right in recent years, and many Republicans might want the seat — including, perhaps, the man doing the appointing, Republican Gov. Ron DeSantis, who is termed out of office in 2026. Remember, DeSantis briefly ran for Senate in 2016 when Rubio was campaigning for president, but shifted gears when Rubio decided to run for reelection. But DeSantis is facing calls by some Republicans, including Sen. Rick Scott, to appoint Republican National Committee Chair Lara Trump, the incoming president's daughter-in-law who previously looked at running in North Carolina's 2022 Senate contest.

The Republican incumbents in the other three states all look set to seek reelection. In Alaska, Sen. Dan Sullivan comfortably retained his seat in 2020, but he could have to contend with outgoing Democratic Rep. Mary Peltola, who just narrowly lost reelection in the state's at-large House seat. In Iowa, Sen. Joni Ernst appears interested in becoming secretary of defense, but she starts as a clear favorite for reelection. And in Texas, Sen. John Cornyn just lost the race to become the GOP's Senate leader, so we shouldn't rule out the idea of a retirement. Still, he's consistently said he plans to run again.

Of course, Democrats not only need to gain seats but also hold onto the 13 they are defending in 2026. That list really starts with Democratic Sens. Gary Peters of Michigan and Jon Ossoff of Georgia, who have to survive in seats in states that Trump narrowly carried in the presidential race. Still, that's on the low end when it comes to the number of highly-endangered seats Democrats will have to defend in 2026, compared to where other non-presidential parties stood in midterms over the past three decades.

This is a very different situation for Democrats than the last time Trump was in the White House. Like in 2026, Republicans in 2018 didn't have many vulnerable seats to defend, helping them limit their losses to Nevada, which Trump had lost in 2016, and Arizona, which he'd narrowly won. But Democrats that year had to defend 10 seats in states that Trump carried in 2016, and the GOP ended up picking up four of those to produce an overall Republican net gain of two seats.

Helpfully for Democrats, seats held by the non-presidential party on the whole tend to not flip to the president's party in a midterm. Trump carried both Michigan and Georgia this year by fewer than 3 points, and dating back to 1994, the out party has lost just three of 13 midterm Senate races in states that the president's party carried narrowly (by fewer than 5 points) two years prior. To use the 2018 example, Democrats held onto three of their four seats in states that Trump carried narrowly (losing just one, in Florida). Their other three losses came in solidly red states Trump had won by at least 18 points (Indiana, Missouri and North Dakota) — and they also held onto seats in solidly red Montana, Ohio and West Virginia. Democrats won't be defending any seats like these in 2026.

Plus, it's proved even more unusual for the non-presidential party to lose a seat in a state it carried in the last presidential election. In fact, the unusually strong GOP midterm in 2002 was the last time that happened: Democrats lost hold of Minnesota, which Al Gore had won by 2 points (although that Senate race was also unusual given the tragic death of Democratic Sen. Paul Wellstone in a plane crash just days before the election). Looking at the 2026 map through this lens, it would be highly unusual for Democrats to lose seats in states like Minnesota, New Hampshire, New Mexico, New Jersey and Virginia that Harris won by between about 3 and 6 points.

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Republicans are early favorites to retain control of the Senate in 2026. They have few vulnerable seats to defend and can afford to lose up to three without losing their majority, due to Vance's tie-breaking vote in a 50-50 Senate. Still, a small sliver of hope for Democrats may lie in the fact that 2026 will be Trump's second midterm cycle as president. Although Trump won't have two consecutive terms in office, his presence in the White House could still tap a bit into what has sometimes been called "the six-year itch" — when voters tire of a president and the opposition performs especially well in that president's second midterm.

Additionally, an especially unpopular Trump could put some GOP-held seats on the board that shouldn't be competitive. For example, when Democrats won the December 2017 special election for Senate in dark-red Alabama, they weren't just helped out by the presence of a terrible Republican nominee (although that was a huge part of it): That race also took place when Trump's approval rating hit its lowest point during his first term in office. Weird things can happen. But Democrats are going to need a lot of things to go their way in 2026 to have a shot at taking back the Senate.