On Thursday night, Senate Republicans delayed a planned vote on a sweeping tax bill that would reduce taxes, particularly on corporations and the wealthy, by billions of dollars and repeal Obamacare’s individual mandate — because they didn’t have the votes to pass it.

But Senate Majority Leader Mitch McConnell has been using a flurry of last-minute dealmaking to win over holdout senators.

Now, there seem to be only a few holdouts left. Probably the most likely way the bill fails at this point is through “no” votes from Bob Corker (R-TN), Jeff Flake (R-AZ), and Susan Collins (R-ME).

Other previous holdouts, such as Sens. Ron Johnson (R-WI), Steve Daines (R-MT), John McCain (R-AZ), and Lisa Murkowski (R-AK), have come on board and said they’d vote for the bill.

Though we still don’t have the text of McConnell’s revisions, a Senate vote on the full bill is planned for Friday, and it would take three GOP defections to kill it. So here are the Republican senators who publicly remain on the fence.

The retiring deficit hawks with nothing to lose: Bob Corker and Jeff Flake

Sen. Bob Corker of Tennessee and Sen. Jeff Flake of Arizona have a few things in common. Both are deficit hawks who have expressed concern that the GOP’s eagerness to cut taxes will lead them to blow up the federal deficit. Both have clashed repeatedly with President Trump this year. And both are retiring in 2018 — which gives their party’s leaders little leverage over them.

The current version of the Senate tax bill would add a little less than $1.5 trillion to the deficit over the next 10 years. But on paper, it would not add to the deficit in years after that — because many of its tax cuts are set to expire.

Here’s the problem: It’s obvious to everyone that Congress will be under enormous pressure not to let any of the bill’s tax cuts actually expire, but rather to extend them. That’s what’s tended to happen in similar situations in the past, and indeed, White House officials and some conservative Republican senators are openly saying that they hope it would happen again.

But if the bill’s tax cuts won’t actually expire as planned, then they’ll naturally keep on adding to the deficit, as Flake has pointed out. “The savings, the score, it just isn’t valid because you know that they’re not going to follow through,” he told Politico recently. “You can’t assume that we’ll grow a backbone later. If we can’t do it now, then it’s tough to do it later.”

Corker, meanwhile, has said repeatedly in recent months that he won’t support a tax bill that adds even “one penny to the deficit.” However, he has sometimes left a bit of wiggle room there. For instance, he’s suggested that he might accept “a reasonable score on dynamic growth,” meaning that he’s basically willing to assume the tax cuts will generate significant revenue by stimulating economic growth.

This week, discussions aimed at winning him over have focused on some sort of “trigger to kick in additional revenues” if the tax bill expanded the deficit too much. But on Thursday, the Senate parliamentarian effectively killed that effort by ruling that the trigger couldn’t pass through the budget reconciliation process with just a majority vote.

The party is trying to come up with some additional revenue to win Corker and Flake over. But as long as McConnell keeps the rest of the Senate GOP together, he can afford to lose Corker and Flake’s votes. Which means he needs to win over...

The moderate: Susan Collins

Next, there’s the perennial tough vote for Republicans to lock down: Sens. Susan Collins (R-ME). She famously voted against the Senate’s Obamacare repeal bill earlier this year. And the Senate’s tax bill includes a major health care-related provision: the repeal of Obamacare’s individual mandate.

Though Collins would prefer the mandate repeal be dropped from the tax bill, she’s lately showed some openness to voting for a bill that includes it — so long as Congress passes other measures to stabilize the health insurance markets.