Former Rep. Tom Suozzi will win back his old House seat in Tuesday's special election in New York's 3rd Congressional District, ABC News projects -- extending his party's largely winning record in such races and further whittling down Republicans' tiny majority in the chamber.
Suozzi dispatched with Republican nominee Mazi Pilip to earn the seat, which encompasses parts of Long Island.
Their race was widely seen as offering the year's first notable clues about how voters, particularly in the suburbs and in swing areas, are feeling about key political issues and about President Joe Biden and down-ballot Democrats heading into November's general election.
At the same time, Tuesday was an off-schedule special election with relatively low turnout to replace disgraced Republican Rep. George Santos after his expulsion, and experts said the contest was shaped in part by local factors, likely limiting how much the results are indicative of voters across the country.
Here are five takeaways.
Once Suozzi takes office, Republicans will be able to afford only two defections on any vote in the 219-213 House, assuming full attendance and no Democrats voting with the GOP.
Republicans have already struggled to unite on major legislation, from funding the government to Ukraine aid to impeachment.
That was underscored when the House last week initially failed to impeach Homeland Security Secretary Alejandro Mayorkas because three Republicans voted against doing so and one Democrat returned from the hospital to vote the same day -- an appearance that surprised Republicans.
House Speaker Mike Johnson of Louisiana, an unlikely chief who won the role just months ago after a historically dysfunctional leadership fight in his party, will now have even less wiggle room in making sure Republicans stick together to pass their key priorities in the remaining 11 months before a new Congress is sworn in.
Government funding deadlines are right around the corner.
MORE: House Republicans impeach Homeland Security Secretary Mayorkas in historic, controversial voteDemocrats' winning streak in special and off-year elections was continued Tuesday, another sign that the party is able to win elections even while being led by an unpopular president whose handling of issues like immigration and inflation is roundly disapproved of by the public.
Democratic hand-wringing about the future has reached a fever pitch in some corners given Biden's dismal approval ratings, especially after special counsel Robert Hur's report on the president's handling of classified information while out of office also included multiple descriptions of his poor memory, which he denies.
However, even with those problems, Democrats have celebrated notable wins after wins since 2018 -- including in recent special and off-year races under Biden, like last year's gubernatorial and legislative races in Kentucky and Virginia, respectively, and in races for state legislative seats across the country to fill vacancies. (There have been glaring exceptions, like in Florida and New York.)
Even in many seats they lost, Democrats overperformed the partisan makeup in the districts.
Suozzi's projected victory is the latest sign that the Democratic enthusiasm sparked by former President Donald Trump after 2016, which escalated after the scrapping of constitutional abortion protections in 2022, is alive and well heading into November -- and members of both parties took note.
"Donald Trump lost again tonight. When Republicans run on Trump's extreme agenda - even in a Republican-held seat - voters reject them," Biden's campaign manager, Julie Chavez Rodriguez, said in a statement.
"Let's just say the quiet part out loud. Donald Trump continues to be a huge weight against Republican candidates. Despite the enormous and obvious failings of Joe Biden, we just lost another winnable Republican House seat because voters overwhelmingly reject Donald Trump," added Nikki Haley, the former South Carolina governor and Trump's lone remaining major primary challenger.
Trump, for his part, argued on social media that a "very foolish" Pilip, who is still a registered Democrat, had failed by not more fully embracing him and the MAGA movement.
Suozzi's win was even sweeter for his party given Democrats' relative wipeout in New York in 2022, when they unexpectedly lost out on House seats on Long Island and in the suburbs to New York City's north -- seats that will now be key to the fight for the House next year.
Still, Suozzi has warned his party that it has work to do with voters, indicating that he in part has run against Democrats' national brand.
"I think my whole campaign is a warning sign for Democrats," he told ABC News in an interview before Election Day. "I've always been somebody who has been battling with my own party. I've always been a centrist ... and they asked me to run. Why? Because they know my message is what we need to be talking about."
Democrats appeared to learn their lesson from the 2022 New York races.
Suozzi's seat was open after he waged a failed bid for governor and the GOP elevated Santos, an unknown quantity who won by about 7.5% in a year that favored New York Republicans amid worries over crime and inflation.
Robert Zimmerman was Democrats' nominee and he ultimately lost a seat that Biden had won handily in 2020.
This year, Democrats went after Suozzi again. He represented the district in Congress for three terms and served in local office before that -- an established track record that he used to set himself apart from the image of national Democrats, particularly on immigration.
Pilip, meanwhile, came in with an impressive background as an Ethiopian-born Jew who served in Israel's military, but her stances on policy were murky, which Suozzi seized on given her lower profile compared to him.
On top of that, Suozzi blitzed the district with events, while his campaign and outside groups swarmed the airways with ads both supporting him and knocking Pilip. Republicans couldn't keep up with Democrats' spending, and Pilip's campaign schedule was unusually lighter than Suozzi's.
MORE: New York 3rd District special election results: Tom Suozzi projected to beat Mazi PilipSome Democrats have worried that Biden's handling of the Israel-Hamas war could hurt his electoral prospects this year, given the outcry from younger and progressive voters that he should focus more on Palestinian civilian casualties as Israel bombards Gaza.
Protesters who have been critical of his backing of Israel have repeatedly appeared at his events, while Republicans use any utterance of criticism of Jerusalem to cast the president as insufficiently supportive of the longtime U.S. ally.
Biden has tried to strike a balance between backing the campaign against Hamas and urging more caution from Israel's military, while Israel insists it takes steps to avoid civilians amid the high death toll.
Tuesday's race on Long Island isn't a perfect microcosm for how the issue will play out this year -- the district boasts a hefty Jewish population and skews more in support of Israel.
The war was also more notable in the special election given Pilip's background and the fact that one of the hostages taken by Hamas during its Oct. 7 terrorist attack on Israel is from the district.
Suozzi came out in strong support of Israel's response, which has drawn pushback from Biden as "over the top," saying he didn't support conditions on aid to Israel, a key demand of many of Biden's more liberal detractors.
Democrats in New York were dogged by concerns over crime and immigration in 2022, and the latter issue has been especially elevated in recent months with New York City receiving thousands of migrants and asylum-seekers sent north from the southern border.
Pilip campaigned by tying Suozzi to the White House's border policies, which Suozzi rejected, saying he wanted a bipartisan deal on the issue while tightening security.
It could be tough for other candidates to replicate his playbook, given that Long Island has a unique political identity, as 538 details. But Suozzi found electoral success as a more moderate Democrat by taking clear stances on immigration reform and crime.
He established a tough-on-crime reputation throughout the campaign, and he repeatedly knocked Pilip for opposing a bipartisan immigration bill in the Senate, arguing she stood in opposition to the legislation while offering no alternatives herself.
"Crime and immigration and taxes is not a Republican message. It's an American message," Suozzi told ABC News. "And Democrats as well as Republicans need to be addressing these issues."