WASHINGTON >> An arcane battle over emergency Federal Reserve powers foiled efforts today to lock down an agreement on an almost $1 trillion COVID-19 economic relief package. Today’s deadlock was just the latest stumble in a partisan, months-long fight over pandemic relief and the lack of progress is backing lawmakers once again up against a government shutdown deadline Sunday night.

Lawmakers on both sides said a provision by Sen. Pat Toomey, R-Pa., that would curb emergency Federal Reserve powers was the sticking point. Republicans are insisting on the Toomey plan, while Democrats are adamantly against it. A compromise was proving elusive, but communications channels are open, as key lawmakers convened in scrums on the Senate floor and as Toomey and Senate Minority Leader Chuck Schumer, D-N.Y., met to exchange ideas.

“I think that we should be able to get a deal done,” Toomey said afterward.

“I think they agreed to go back and write down what they were saying, so everybody can read it and exchange paper,” said Sen. John Cornyn, R-Texas.

The latest pratfall likely upends hopes for a House vote Sunday and quick Senate action on an agreement that’s virtually ready save for Toomey’s provision.

“That has to be resolved. And then everything will fall into place,” said House Speaker Nancy Pelosi, D-Calif. “It’s a very significant difference.”

A new deadline of midnight Sunday for a government shutdown served as a backstop for the tortuous negotiations, which were being conducted in secret largely among the top four leaders in Congress.

“We need to conclude our talks, draft legislation, and land this plane,” said Senate Majority Leader Mitch McConnell.

Toomey defended his controversial provision in a floor speech, saying the emergency powers were designed to stabilize capital markets at the height of the COVID panic this spring and are expiring at the end of the month anyway. The language would block the Biden administration from restarting them.

Even Toomey said this week that his provision “could be seen as redundant,” but neither he nor his Democratic adversaries were backing down from the fight, though compromise language was being shuttled back and…