Democrats are casting a nervous eye on a small group of publicly undecided senators in their ranks as Republicans target a coveted prize in the Senate impeachment trial — a bipartisan acquittal of President Trump.

Under the spotlight are two centrist mavericks who won election last year — Sens. Joe Manchin III (D-W.Va.) and Kyrsten Sinema (D-Ariz.) — as well as Sen. Doug Jones (D-Ala.), who will face voters this year after a long-shot win in a special election in 2017.

“I talk to those three every day; I don’t have a sense on where they’re going to be in the end,” said Sen. Chris Murphy (D-Conn.), who described the coming verdict as a “conscience vote” in which senators are leaving colleagues to reach their own conclusions.

Senators hardly need to be reminded of the stakes, however. Public attention in the early stages of the trial has been heaped on the handful of Republican moderates who are set to determine whether unheard witnesses and unseen documents will be admitted to the proceedings after the White House stonewalled Congress, but the wavering Democrats could have a significant bearing on the ultimate political ramifications of the verdict.

Multiple Republicans suggested Wednesday that any defections would fuel their campaign to dismiss the nearly five-month impeachment probe as a partisan witch hunt, while undermining Democrats’ attempts to cast doubt on the fairness of the Senate trial and use the impeachment probe as a cudgel in the upcoming elections.

“Everybody’s focused on one thing, and that is whether or not the Republicans will stay united,” said Sen. Tim Scott (R-S.C.). “The truth of the matter is that there are at least two if not three Democrats that can separate from their caucus, which would be a huge win because any bipartisan acquittal is big deal.”

Manchin, who has sought to maintain a working relationship with Trump even after the president campaigned heavily against him last year, is widely seen as the most likely Democratic vote for Trump’s acquittal. That speculation has been based not only on the tilt of his state, which voted for Trump by 42 percentage points in 2016, but his history of backing the president on key votes and the 72-year-old’s refusal to rule out a 2024 reelection run or a second stint as governor.

In an interview Wednesday, Manchin invoked his home state repeatedly as he insisted that he was tuning out pressure from either party: “I’m here because of West Virginia. I’m not here because of any senator, okay?” he said. “No one’s my boss except West Virginia.”

Jones is facing an even more precarious position in a similarly pro-Trump state. The surprise winner of a special election, Jones will face voters in November, and Republicans consider that by far their best opportunity to flip a Democratic seat in the 2020 cycle. But he also has little chance of reelection if he alienates his party’s base voters by opposing Trump’s removal.

“In every case, a judge says: ‘Please don’t start deliberating. Please don’t make up your mind until you hear all the evidence,’ ” Jones, a former U.S. attorney, told reporters Wednesday. “Am I leaning on different things? Sure. But I ain’t going to tell you guys that, for God’s sake.

In public comments this week, Jones suggested he is entertaining a split decision — convicting Trump for abuse of power while acquitting him for obstruction of Congress — although he suggested Wednesday he might be moving away from that view: “The more I see the president of the United States attacking witnesses, the stronger that case gets,” he said, after Trump tweeted sharp words about John Bolton, his former national security adviser.

More than any other Democratic senator, Sinema has kept her thinking private.

“I will treat this process with the gravity and impartiality that our oaths demand and will not comment on the proceedings or facts until the trial concludes,” she said in a statement at the outset of the trial and has assiduously avoided addressing reporters since.

But Sinema is also perhaps the most unpredictable member of the Senate Democratic ranks, joining Manchin and Jones in February to confirm Attorney General William P. Barr before taking a week-long break mid-session to compete in a New Zealand triathlon.

Spokeswoman Hannah Hurley, declining an interview request on Sinema’s behalf, pointed to that initial statement in explaining “how seriously she takes this process, the oath that she swore, and what that oath demands of her and every other senator.”

Some Republicans have their eyes on a fourth Democrat: Sen. Gary Peters of Michigan, who is seeking a second term this year in a race that is looking increasingly competitive due to the aggressive fundraising of Republican businessman John James. But much like Jones, other Democrats see little chance Peters breaks faith with the vast majority of his party’s voters who favor Trump’s removal.

Peters said Wednesday that he remains undecided and that he would wait for the two-day question-and-answer process to conclude.

“I’ve learned through a lot of committee hearings: It’s not the opening comments that are the most interesting. It’s the questions and answers,” he said. “I think it’s important to keep an open mind.”

Democrats have been encouraged that all four senators have stayed publicly united on the question of summoning additional evidence. Over 12 procedural votes last week, party lines held firm on all but one question, where Sen. Susan Collins (R-Maine) joined with Democrats.

Trump and his allies have already sought to put a spotlight on the modest partisan crossover in the House, where Rep. Collin C. Peterson (D-Minn.) voted against both articles of impeachment, Rep. Jared Golden (D-Maine) voted against one, and Rep. Jeff Van Drew of New Jersey switched to the GOP after opposing both. They have at the same time dismissed the vote of Rep. Justin Amash (I-Mich.), a conservative former Republican who left the party last year after facing blowback for his attacks on Trump.

In the Senate, Republicans could be facing defections of their own. Collins as well as Sens. Mitt Romney (R-Utah) and Lisa Murkowski (R-Alaska) have signaled that their votes remain in flux. But many in the GOP believe that a Democratic crossover is more likely — and potentially more significant.

“It would mean once again,” said Sen. Kevin Cramer (R-N.D.), “that the only bipartisan support is for the president.”

Senate Minority Whip Richard J. Durbin (D-Ill.) played down the Republican pressure campaign and, like Murphy, said there has been “no pressure and no demands and no retribution suggested for anyone” in the Democratic ranks. Any claims of bipartisanship on Trump’s part, he said, would ultimately be flimsy.

“If I get one Republican vote, I talk about my ‘bipartisan measure’ — that’s natural around here. But you know, I think people will understand if it’s just one, two, three people as opposed to a larger number,” he said, pointing to the 1999 Bill Clinton impeachment, where five Republicans joined Democrats to reject one article, and 10 rejected another. “I think that was bipartisan. It’s in the eye of the beholder.”

Rachael Bade, Robert Costa, Paul Kane, Seung Min Kim and Erica Werner contributed to this report.