Democrats up for re-election in battleground states face a bind in the Senate as the impeachment trial for Department of Homeland Security (DHS) Secretary Alejandro Mayorkas is expected to begin this month over his role in the ongoing crisis at the southern border.

Several Republican Senate sources told Fox News Digital they expect the pressure to ramp up for lawmakers such as Sens. Jon Tester, D-Mont., Jacky Rosen, D-Nev., Tammy Baldwin, D-Wis., Sherrod Brown, D-Ohio, and Bob Casey, D-Penn., who face competitive re-election races in November.

Voters in each of the senators' states have indicated strong concerns over the state of the border.

Republican senators recently accused Tester of being unwilling to vote on border or immigration-related amendments during negotiations over the $1.2 trillion spending package that caused a brief partial government shutdown before being passed last month. Tester's office denied the claims. 

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One senior Republican Senate source predicted Tester would be similarly pushed during the impeachment trial procedure: "He’ll have to go on the record with it. No way out," the source said. They noted that Brown would also be put to the test in the Mayorkas trial. 

A representative for Tester told Fox News Digital on Wednesday, "Senator Tester will review the articles when they are sent over to the Senate."

The House passed two articles of impeachment against Mayorkas in early February but held onto them until after the appropriations process finished. In a letter last week, House Speaker Mike Johnson, R-La., revealed his intention to deliver the articles to the Senate on April 10 and urged Senate Majority Leader Chuck Schumer, D-N.Y., to move quickly on a trial. 

When the articles are delivered, "all senators have to be sworn in as jurors and sign the book," a senior GOP source said. 

"We actually go into trial mode, but Schumer will put forward a vote to dismiss it," the source predicted.

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Schumer's office did not provide comment to Fox News Digital.

"Everything is simple majority," the source noted, meaning only 51 of the 100 senators are necessary to move forward with any action. 

While Senate Democrats have largely dismissed the charges against Mayorkas as meritless and political posturing, the lawmakers who are competing in close races in the general election may be influenced by the growing concern over the border among their constituents. In a March Fox News Poll, 41% of all registered voters agreed the situation at the southern border is an emergency. This included 65% of Republicans, 31% of independents and 20% of Democrats.

As a result, the vulnerable Democrat senators are certain to be met with attacks on the campaign trail from their Republican opponents, who will pose the question of their seriousness on the border crisis. In a February memo from National Republican Senatorial Committee political director Tim Edson that was obtained by Fox News Digital, Senate candidates were advised to hold their Democrat counterparts accountable.

"We cannot allow Senate Democrats to sweep the Biden Administration's failures at the southern border under the rug," it reads. "Democrats caused this crisis, and voting to acquit Mayorkas is a vote to allow the continued invasion of our country."

Tester's opponent, Republican Senate candidate Tim Sheehy, said in a statement that "the Senate should hold a full impeachment trial."

"Senator Jon Tester wants to avoid a trial and let Mayorkas off the hook because they BOTH support the radical Left’s push of open borders and letting illegal immigrants flood into America. We deserve accountability!" he continued.

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Representatives for Rosen, Baldwin, Brown and Casey did not provide comment to Fox News Digital.

"If Bob Casey is serious about securing the border, he'll urge Chuck Schumer to move this inquiry forward and hold them accountable," said Pennsylvania Republican Senate front-runner Dave McCormick in a statement to Fox News Digital.

Spokesperson Ben Voelkel for Wisconsin Republican Senate front-runner Eric Hovde said in a statement, "Sen. Baldwin needs to hold [Mayorkas] accountable. If she doesn't, Wisconsin voters will hold her accountable for her inaction."

"If Sherrod Brown cares about hardworking Ohioans who have been impacted by the border invasion and fentanyl crisis, he will hold Mayorkas accountable in the Senate trial," said Reagan McCarthy, spokesperson for Ohio Republican Senate candidate Bernie Moreno.

Sen. Joe Manchin, D-W.Va., who has occasionally been out of step with Democrats, appears likely to stick with his caucus in the likely case they look to dismiss the trial quickly. In February, he told Politico that the forthcoming impeachment was "Pure crap," adding that he wants "No trial at all."

Manchin's office referred Fox News Digital to his previous comment.

Republican strategist Brian Walsh, a former staffer for Sen. John Cornyn, R-Texas, said, "It highlights a huge political vulnerability for Democratic Senators like Jon Tester, Sherrod Brown and Bob Casey going into the 2024 election."

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They will be forced to "pick a side" between their base and "the majority of voters, including independents" who say the border is the most important problem in the country, Walsh added.

As the senators face a difficult decision, it's not clear that all Republicans will be on board to continue the trial. Each vote matters, given the Senate's narrow 49-51 split between Republicans and those in the Democrat caucus. 

Sen. Mitt Romney, R-Utah, criticized the idea of a trial in late February, writing on X, formerly known as Twitter, that it "might be great politics, but it’s not the remedy for bad policy & would set a terrible constitutional precedent."

Romney's office did not provide comment to Fox News Digital. 

Other concerns for the impeachment effort are Sens. Lisa Murkowski, R-Alaska, and Susan Collins, R-Maine, who have gone against the conference previously. Neither of their offices provided comment to Fox News Digital on the subject.

Meanwhile, Mayorkas is set to appear on Capitol Hill on April 10, the same day the articles of impeachment are expected to be delivered to the Senate, for an unrelated hearing before the House Appropriations Homeland Security Subcommittee regarding the department's fiscal 2025 request.

DHS did not provide comment to Fox News Digital.