WASHINGTON — The political dynamics of Brett Kavanaugh's Supreme Court nomination have shifted since allegations surfaced that he assaulted a girl when he was in high school.

But the same handful of publicly undecided Republicans and Democrats still hold the fate of Kavanaugh's nomination in their hands as lawmakers try to figure out the best way to reconcile the allegations of Christine Blasey Ford with Kavanaugh's denial — and whether their votes would be affected by the outcome of that exercise.

Because Republicans hold a 51-49 majority in the Senate and the vice presidency, it would take only two GOP defections to sink the nomination if all Democrats voted against Kavanaugh.

Here are six senators — three Republicans and three Democrats — to keep an eye on:

Susan Collins, R-Maine

Collins spoke to Kavanaugh about the allegations during a phone call Friday, and she told The New York Times afterward that it was "not fair" to either him or Ford that Democrats had not called attention to them earlier in the process.

The lone remaining New England moderate among GOP senators — and one of only a half-dozen GOP women in the chamber and one of only two who support abortion rights — Collins has not yet said how she will vote on Kavanaugh's nomination. Her support would give other Republicans political cover to vote for confirmation, while her opposition could create pressure to sink the nomination.

On Monday, she tweeted that Ford and Kavanaugh "should both testify under oath" before the committee.

Lisa Murkowski, R-Alaska

Murkowski, the other Republican woman who supports abortion rights, also hadn't publicly announced how she would vote before the allegations surfaced. As such, vote-counters have been looking for clues about her intentions throughout the process.

When the nomination was first announced, Murkowski signaled she was receptive to Kavanaugh. After they met in August, she said they had a "substantive conversation" about a variety of topics, including issues of particular importance to Alaska residents.

Now, Murkowski says she thinks the Judiciary Committee "might have to consider" discussing whether to postpone its vote scheduled for later this week. Though they are often discussed together, she and Collins could break from each other if Kavanaugh gets an up-or-down vote on the Senate floor.

Jeff Flake, R-Ariz.

There's no wildcard in the Senate right now quite like Flake, who, unlike the rest of the swing voters on Kavanaugh, sits on the Judiciary Committee. He's a conservative for whom Kavanaugh's judicial philosophy and leanings should be comforting. He's even said he's inclined to support the judge.

But Flake is retiring from the Senate, which means he doesn't have to worry about angering the majority of his Republican constituents with a "no" vote, and it would be an understatement to say he's no fan of Trump. Flake said Sunday that he wouldn't be comfortable voting "yes" in committee if the panel vote goes forward without more information.

Does that mean he would vote no or just that he would be uncomfortable? It's not clear.

Sen. Heidi Heitkamp, D-N.D.

On Monday, Heitkamp called on the Judiciary Committee to investigate Ford's charges but stopped short of saying that the committee vote should be delayed. She's one of three Democrats who voted for Trump's last Supreme Court pick, Neil Gorsuch, and one of the most politically vulnerable Democrats in this November's midterms.

Like other red-state Democrats — Trump won North Dakota with 63 percent of the vote — Heitkamp has followed Democratic leaders' admonition to not show her cards before she has to. For weeks, she hasn't budged from her position on Kavanaugh, which is that she will "continue reviewing his record."

Sen. Joe Donnelly, D-Ind.

Donnelly also voted for Gorsuch, which has deprived Trump of a talking point during his visits to Indiana to campaign for Republican Senate nominee Mike Braun. Donnelly was one of the first Democrats to schedule a meeting with Kavanaugh as Braun applied pressure on him to do so.

But Donnelly, who hasn't said how he'll vote, was also among the first to call for a delay of the committee vote Sunday after Ford's allegation became public.

"The allegations made against Judge Kavanaugh are serious and merit further review," he said in a statement. "Given the nature of these allegations, and the number of outstanding questions, I believe the Judiciary Committee should hold off on Thursday's scheduled vote."

Sen. Claire McCaskill, D-Mo.

If there's one vulnerable sitting Democrat whose opponent is most comfortable talking about the Supreme Court, it's McCaskill's foe, Missouri Attorney General Josh Hawley.

A former law clerk for Chief Justice John Roberts, Hawley likes comparing his support for "constitutional conservatives" to McCaskill's backing of "liberals" for the high court. He's accused McCaskill of being "wrong on Supreme Court nominees every time" — including her support for President Barack Obama's picks and her opposition to Gorsuch — and he's capable of citing chapter and verse from past decisions in a way that few candidates can.

Like her Democratic colleagues in tough races, McCaskill has been mum about how she'll vote. But, given her record on Supreme Court nominations and the new allegations against him, it would be a major surprise if she backed Kavanaugh.