Senate are inching closer to burying to expand the and provide breaks for businesses, issuing a series of demands that would most likely disrupt the coalition that enabled it to pass the House.

The $78 billion bill, negotiated by House Ways and Means Committee Chair Jason Smith, R-Mo., and Senate Finance Committee Chair Ron Wyden, D-Ore., by a vote of 357-70 in January, a in a divided Congress that has struggled to function. But it has languished in the Senate, where key Republicans have said they'll kill it unless it includes major revisions. Senate have 51 seats, and they need 60 votes to break a filibuster.

But with tax filing season close to finishing and election-year politics heating up, there's no hint of a resolution in sight. Democratic leaders are eager to pass the legislation, which, according to , would benefit about 16 million children in low-income households. Some Republicans openly warn they may sink it.

Sen. Thom Tillis, R-N.C., a member of the Finance Committee, said he'd be happy to see the entire tax bill fade away.

"I hope so," Tillis said, adding that it doesn't have the necessary 60 votes to pass in the Senate today.

"I honestly think unless Sen. Crapo indicates they're negotiating in good faith, I don't see how they have a path," he said, referring to Mike Crapo of Idaho, the ranking Republican on the Finance Committee. "If it's just about the vote on the floor, I don't think they have a path."

The bill would expand child tax credits and lift the $1,600 cap on refundability and adjust it for inflation, with the biggest benefits going to multi-child families with low incomes. The bill also includes some business tax breaks, including for research and development and small-business expensing that were key to getting GOP support in the House.

Many GOP senators are deferring to Crapo on the path forward, including Minority Leader Mitch McConnell, R-Ky.

Crapo told NBC News on Tuesday that he still has problems with "a number" of provisions. He said he wants to eliminate a "look-back" policy that would let a taxpayer use a previous year's income if it yielded a larger child tax credit, arguing that the current language weakens the work requirement. Saying the bill would "create entitlement spending that would generate significantly higher deficits," he called for spending cuts to fund the child tax credit expansion.

"Those are just the start," Crapo said, adding that he likes the business tax breaks. But about the individual tax provisions: "There's a multiplicity of issues. And until we get at least engagement on the issues, then I can't make any kind of predictions."

Sen. Chuck Grassley, R-Iowa, a senior member of the Finance Committee, said he agrees with Crapo about limiting the parameters of the child credits.

Asked whether the bill is dead, he said that wasn't his announcement to make. "You can't say that until Crapo says it," Grassley said. "Crapo's the guy who's got to say that."

The demands are a tall order. Crapo indicated that he isn't satisfied with using changes to the employee retention tax credit as ; ditching that idea would require starting from scratch.

Rep. Richard Neal, D-Mass, the ranking member of the tax-writing Ways and Means Committee, warned that major changes in the Senate would fracture the coalition in the House. He said there's "no question" Senate Republicans are trying to sink the bill to deny President Joe Biden an achievement in an election year.

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Sen. Josh Hawley, R-Mo., proposed adding the to the tax bill, aimed at benefiting those injured in uranium mining and the Manhattan Project, the program that developed atomic bombs during World War II, saying it might attract GOP votes.

"This tax bill looks like, to me, it's in very serious trouble," he said Tuesday. "It's on life support. So I think if they put those things together, that might unlock support. I know it will get my vote."

But Crapo summarily shot the idea down.

"I will support it when we fix the provisions in the bill," he said. Adding the radiation compensation act "does not fix the underlying bill."

Sen. Ron Wyden, D-Ore., the chairman of the Finance Committee, said he wanted the bill passed "months ago" but isn't giving up — and he voiced frustration over the negotiations with Republicans.

In an interview, Wyden said that he offered to give the GOP its top demand but that it didn't adequately move the needle.

"If I had my way, this would have been done months ago. And the reality is this wasn't something that Senate Republicans wanted to do," Wyden said. "In the most recent exchange, I gave them what's individual Republican senators' top ask, which was to get rid of the look-back. I was given, by them, something that wouldn't have gotten a single Democratic vote in the Senate. Not one. So there you have it. We're continuing to try to find common ground."

Wyden touted the package's popular benefits for families and businesses and taxpayers through anti-fraud measures, urging his Senate colleagues to get behind it.

"You're going to let all this fraud continue and not do anything?" Wyden said. "You're going to say no to 16 million young people? You're going to say no to those who are the small businesses and say yes to a [Donald Trump] presidential campaign that's going to be based on being more sympathetic to billionaires' tax needs?"

Senate Majority Leader Chuck Schumer, D-N.Y., was noncommittal Tuesday when he was asked whether he'll put the bill to a floor vote.

"Look, I'm all for the package. If there are enough votes to move it forward in the right way, yeah, we'll try to get it on the floor," Schumer told reporters at his weekly news conference. "But right now, we don't think — they're trying to get enough votes. The sponsors are trying to see if there are enough votes."