Tester has been a GOP target long before he got in the president’s crosshairs.

The Democratic senator’s last two elections were close – he won in 2006 by less than 1 percent and won in 2012 by 1 percent – and Trump took the state by 20 points in 2016.

But Republicans are battling it out in a four-way primary and Trump took their strongest option for a nominee when he nominated then-Rep. Ryan Zinke to be his Interior Secretary. Tester voted to confirm him.

Tester, however, provoked Trump’s ire with his questions about Jackson’s qualifications for the Veterans Affairs job, which including him releasing a detailed list of allegations made against Jackson – that he handed out medications without prescriptions and that he got drunk and wrecked a government vehicle. Ultimately, Jackson withdrew from consideration.

On Saturday, the president tweeted: “Secret Service has just informed me that Senator Jon Tester’s statements on Admiral Jackson are not true.” He added: “Tester should lose race in Montana. Very dishonest and sick!”

Secret Service has just informed me that Senator Jon Tester’s statements on Admiral Jackson are not true. There were no such findings. A horrible thing that we in D.C. must live with, just like phony Russian Collusion. Tester should lose race in Montana. Very dishonest and sick!

— Donald J. Trump (@realDonaldTrump) April 28, 2018

The Secret Service said it has found \"no information that would indicate the allegation is accurate\" – that he had been drinking and wrecked a government vehicle.

Trump doubled down, however. At his rally in Michigan on Saturday night, he said: “I know things about Tester that I could say too, and if I said them, he’d never be elected again.”

The president did not offer any additional details.

Robert Saldin, a professor at the University of Montana, said Trump’s attack on Tester came as a surprise in Montana.

“It was a little bit of surprise in the sense that Tester really has made an effort to not aggressively go after President Trump like many Democrats across the country do,” he said. “He’s really tried not to be in an adversarial position with Trump.”

He added: “It hurts Tester at least a little bit. This was not what they were hoping.”

The president has shown a willingness to get involved in Senate contests although he is usually touting a GOP candidate instead of attacking a Democrat. The Senate is where Republicans see their best chances of holding onto a chamber of Congress and, if Democrats retake the House, they will need it as a firewall on Capitol Hill.

But how much influence Trump will have in the Montana contest – or in any of the competitive Senate contests -- remains to be seen.

“To the extent that the president is the leader of party and would like to see his party do well in the elections I’m not sure that this changes anything. The president might be upset with Tester but if he was doing he was job he’d be campaigning against him anyway,” said Rodell Mollineau, a Democrat strategist and partner at Rokk Solutions.

And, he said, it also reminds Democrats that none of them are safe from the president or his twitter feed.

“I think it’s a bad strategy for anyone to think the president has ADHD and might forget you’re running,” he said.

Tester, in response to the president’s attacks, said he has a duty to protect veterans.

“It's my duty to make sure Montana veterans get what they need and have earned, and I'll never stop fighting for them as their senator,” he said in a statement.

Tester’s Republican opponents are using Trump’s attacks to parlay attacks of their own, mainly to claim the senator isn’t a champion for veterans.

Montana has one of the highest per capita veteran populations in the U.S with about 1 in 10 residents are veterans, according to the Veterans Health Administration.

“What Jon Tester did to Adm. Jackson is also representative of the way veterans in general have been treated by the VA and despite Tester's claims to the contrary, he has failed them,” said Kevin Gardner, the campaign manager for GOP candidate Troy Downing, in a statement.

And Russ Fagg, another Republican contender, accused Tester of putting politics first.

“Jon Tester is once again putting partisan politics ahead of Montana veterans. I agree with President Trump that Jon Tester will have a big price to pay this November when Montanans hold him accountable for his liberal obstructionism,” he said in a statement.

Matt Rosendale, who is considered the front-runner for the GOP nomination, offered multiple tweets criticizing Tester and retweeting the president’s attacks.

Cutting the budget is personal. If we keep government spending down, that's more money in your pocket. I've not only cut spending, but refused a pay raise too, so you know I mean business. SIGN my petition & give the government a haircut >> https://t.co/0z9gVn1WCS #mtsen #mtpol pic.twitter.com/2Pbbuxl575

— Matt Rosendale (@MattForMontana) April 27, 2018

The fourth candidate, Albert Olszewski, is a physician and new to politics.

The four contenders are in a tough fight to come out of the June 5th primary. They are fighting for attention and traction.

Rosendale and Downing are the two most emphasizing their ties to the president.

Downing, a veteran, is bringing out former Trump National Security Adviser Michael Flynn to campaign for him on Sunday.

One Senate Democratic aide dismissed concerns Trump may get involved in the GOP primary and endorse a contender.

“I think whoever comes out of this primary is going to be so damaged by the attacks their fellow Republicans have leveled against them and would have had to spend resources to make it through this race – those two factors will be the driving elements in this primary,” the aide said.

“Whoever comes out of this will be damaged and broke.”

Tester has easily outraised his four GOP rivals, none of whom raised over $500,000, according to their Federal Election Commission reports. The senator, meanwhile, raised $2 million in the first quarter of 2018 and had $6.8 million cash on hand.

He has also touted his work on veterans’ issues repeatedly during his time in office.

Saldin said Trump’s move could end up reminding voters of Tester’s work in that area.

“It reminds everyone he’s engaged in veterans’ issues. This is a big veterans state. The veteran voting block is a big deal in Montana,” he said.

Tester is the ranking member on the Senate Veterans Affairs Committee and has voted for all 13 of the president’s VA nominees.

His first campaign ad focused on the 13 of his bills that Trump has signed into law, most of which deal with veterans’ issues.

And working with the president could be a smart strategy for any endangered Democrat.

Matt Canter, a former spokesman for the DSCC who’s now with Global Strategy Group, said it makes sense for red state Democrats to work with the president when it’s best for their states.

“I think they should be very vocal with they agree with him and very vocal when they don’t,” he said. “I do think voters want to see them work with him to get things when it’s in the best interest of their constituents.”

Steve Murphy, a longtime Democratic strategist, agreed.

“Swing voters always prefer less fighting and more non-partisan problem-solving. A lot of Trump voters wanted to shock the system in 2016, but voters swing like a pendulum do and now they’re seeking an end to the chaos,” he said.

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