Whether or not the US economy sinks into a coronavirus-triggered recession comes down to Donald Trump and Chuck Schumer, the Senate's top Democrat who suddenly finds himself as the most powerful man in Washington.

Whether or not Mr Schumer can strike a deal with the president, the man who mocks him as "Cryin' Chuck," and Treasury Secretary Steven Mnuchin, a former Democrat, will decide the fate of a $1.6trn economic stimulus package that as late as Saturday evening appeared on track for quick passage in both chambers before Mr Trump signed it into law.

Mr Schumer has more of a reputation as a political fighter than a bipartisan dealmaker, making the precarious moment an opportunity for the New York Democrat to score a major legacy victory.

As he aims to secure more assurances from the Trump administration that a massive fund within the still-under-construction bill to help companies comes with greater oversight provisions to ensure the monies are being spent properly, Mr Schumer also must consider his most vulnerable members in November's elections.

Democratic strategists say Mr Schumer is optimistic there is an outside shot Democrats might wrestle the majority away from Republicans – or at least gain clout by stealing a few seats in places like Maine or Colorado to further shrink Majority Leader Mitch McConnell's 53-47 majority.

Roll Call, a prominent Capitol Hill-focused publication, listed Alabama's Doug Jones, Michigan's Gary Peters, and New Hampshire's Jean Shaheen – all Democrats – among the top 10 most vulnerable senators.

Mr Schumer must balance tactics and strategy to ensure his party keeps each seat even while possibly blocking additional floor votes like a procedural one Mr McConnell teed up Sunday evening.

Blocking those votes will give him more time to negotiate directly with Mr Mnuchin, who has emerged as the Trump administration's most effective envoy to Congress. He has already brokered several major deals with Speaker Nancy Pelosi.

Like just about every national or state public official speaking about the coronavirus outbreak, Mr Schumer early Monday morning sent mixed messages.

In one breath he laid out a litany of unresolved issues holding up an economic stimulus package that both parties on the Hill and Mr Trump say is desperately needed as millions of workers are being laid off and much of American economic life slows or already has been shut down.

"There were some serious problems with the bill leader McConnell laid down. Huge amounts of corporate bailout funds without restrictions or without oversight – you wouldn't even know who is getting the money," he said. "Not enough money for hospitals, nurses ... masks – all the health care needs," the minority leader said.

He also griped that the emerging measure contains "no money for state and local government, many of whom would go broke." He then appeared to signal a deal remains a long way off, even as US stock markets stumbled a few hours later as the trading week resumed, saying the sides are far apart on "many other things."

But he also said he hopes the negotiators can reach a final deal before Monday afternoon.

Mr Trump appears to know he needs his fellow-New Yorker after years of clashing and rhetorical jousting between them. The president was noticeably conciliatory towards Senate Democrats during a Sunday night press briefing.

"But I think that the Democrats want to get there. And I can tell you for a fact, the Republicans want to get there," Mr Trump said.

Acknowledging the stakes of reaching a final agreement, the president added: "And I don't think anybody actually has a choice."

Mr Schumer, now with outsize power because of Senate rules that protect the minority party and require 60 votes to get to a final vote on legislation, will have a choice to make early this week.

Senator Chris Coons, a Delaware Democrat and Schumer ally, made clear Monday morning that his party is as concerned with helping local governments stay out of the red as much as they are worried about the $500bn fund to help businesses.

"The president moved forward the tax due date for the federal taxes, which was a good move that I support, that also means lots of states and counties have their tax filing date moved forward two months," he said. "And the lack of sales tax means a lot of local governments are really hurting."

Mr Coons acknowledged it likely looks to the outside world like lawmakers merely are "bickering," but he also vowed "we will get this done."

But politics still could trip up the talks – or further slow them.

House Minority Leader Kevin McCarthy of California, a close Trump ally, echoed Mr Schumer and Mr Coons on Monday by saying, "We are closer than we had been."

But then he issued a broadside against Mr Schumer and Ms Pelosi, who said on Sunday House Democrats plan to release their own stimulus bill, which is widely expected to be significantly different than the Senate's attempt at a bipartisan compromise.

"She's playing political games, and she never should have said that. There is nobody in the House here but Nancy and ... myself," he said. "She cannot craft another bill. Time is of the essence. People will lose their job today because of what Schumer and the others are portraying and doing.