A $78 billion package of tax breaks for families and businesses passed the House on an overwhelming bipartisan vote. But key GOP senators demand big changes — or else.

Senate Republicans are inching closer to burying a bipartisan bill to expand the child tax credit 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., passed the Republican-led House by a vote of 357-70 in January, a rare feat 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 Democrats 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 one analysis, would benefit about 16 million children in low-income households. Some Republicans openly warn they may sink it.