Beware of Democrats bearing votes: The Republican leadership’s tenuous bipartisan deal to pass a “cromnibus” today may be falling apart.

The bargain would fund most of the federal government through the end of next September, while funding the Department of Homeland Security just through the end of February. Passage would have surrendered control over budgets the Republican Congress should get to write next year and suggested, to take a skeptical interpretation, that Republicans have little interest in fighting President Obama’s unconstitutional immigration orders.

But now Democrats, Senator Elizabeth Warren and House minority leader Nancy Pelosi prominent among them, are agitating against the cromnibus and may prevent it from passing the House. (They’ve taken issue with the bill’s repeal of a financial regulation that prevented federally insured banks from trading in custom derivatives — a minor issue either way.) Many Republicans, meanwhile, are rightly dissatisfied with the cromnibus and are planning to vote against it — it cleared a procedural vote today by just two votes.

With funding authorization for the government expiring tonight, it’s possible both chambers will agree to hold off a shutdown for a few more days. The better option, though, would be a short-term funding bill, of two or three months, that keeps spending at current levels.

It would enable Republican leadership to set spending priorities in the new year, with whatever policy riders they want. It would potentially set up a clean fight next year between the president and Congress on his unilateral changes to immigration law.

Harry Reid, who will in large part control the Senate’s approval of any bill to keep the government open, may not love the idea, and Nancy Pelosi may not either. But Democrats’ refusing such a plan would amount to shutting down the government when they’re being offered a clean continuing resolution to keep it open.

It’s time for a good bipartisan compromise with no special-interest deals or last-minute surprises — a short-term funding bill.