Washington (AFP) - The bill hammered out by US leaders to prevent the country from a catastrophic default on its debts will face one final and potentially perilous hurdle this week: Passing a divided Congress.

Lawmakers return Tuesday from a holiday weekend with precious few days to review, debate and ultimately greenlight a measure intended to extend US borrowing authority in exchange for White House policy concessions, notably caps on federal spending.

Top Republicans and Democrats have scrambled to secure congressional support for the measure, with President Joe Biden saying Monday he feels “very good” about its prospects despite having just days left before the government starts running out of money.

The weekend deal, reached by Biden and House Speaker Kevin McCarthy after weeks of frantic negotiations, faces opposition from the progressive and hard-right wings of their respective parties.

Ultra-conservative Republicans feel McCarthy should have secured far deeper spending cuts in exchange for raising the debt ceiling and allowing the government to keep borrowing money.

The left wing of the Democratic Party is equally unhappy that Biden agreed to any spending limits at all.

The House Rules Committee meets Tuesday, a crucial test to see whether McCarthy’s own party, which controls the panel, can agree on a full chamber vote on the bill, now anticipated on Wednesday.

– Delay tactics –

Biden and McCarthy both say they believe the bill will pass the House and then move swiftly to the Senate.

“I never say I’m confident what the Congress is going to do. But I feel very good about it,” Biden said Monday, adding that he had spoken to lawmakers.

Any organized dissent could force some nerve-shredding delays.

The key deadline is June 5 – when, according to Treasury estimates, the government will no longer have the funds required to pay all its debts and bills.

If that scenario morphs into a full-fledged default, the repercussions would be disastrous for the US and wider global economy.

The basic framework of the deal lifts the federal debt ceiling, which is currently $31.4 trillion, for two years – enough to get past the next presidential election in 2024.

In return, the Republicans secured some limits on federal spending over the same period.

As they finalized the text Sunday, Biden and McCarthy both went into hard-sell mode to shore up support in their parties.

Biden’s message to dissident Democrats, he said Monday: “Talk to me.”

– Win, win –

Biden and McCarthy were backed by vocal spin operations, both insisting the agreement represented a victory for their side.

“You want to try to make it look like I made some compromise on the debt ceiling – I didn’t,” Biden told reporters.

McCarthy, for his part, touted the agreement as a “historic series of wins.”

But like Biden, McCarthy will have to quell members of his own party who aren’t keen on the bill.

“I want to raise the debt ceiling. It’d be irresponsible not to do it,” Senator Lindsey Graham told Fox News Sunday.

“But what I will not do is adopt the Biden defense budget and call it a success,” Graham said, calling for bigger increases to the Pentagon’s budget than currently agreed.

“I will not be intimidated by June 5.”

Chip Roy, a House Rules Committee member, also foreshadowed a pitched battle over the bill, saying he and some fellow Republicans oppose it.

“There’s going to be a block of us that are a no,” Roy told a Fox News reporter, in quotes that were reposted by the congressman’s office. “We should kill this.”

Another Republican tweeted out a vomit emoji in response to the deal.

In reality, the agreement represents a mutual climb down of sorts from Democratic and Republican negotiators.

Biden had initially refused to negotiate over spending issues as a condition for raising the debt ceiling, accusing the Republicans of taking the economy hostage.

And the big cuts that Republicans wanted are not there, although non-defense spending will remain effectively flat next year, and only rise nominally in 2025.

McCarthy’s wafer-thin House majority will require significant Democratic backing to balance out Republican dissent.

At the same time, a member of the House Progressive Caucus, Ro Khanna, said a large number of fellow Democrats were still “in flux as to where they’re going to be on this.”

Democrats narrowly control the Senate, and individual senators could try and stall the bill with amendment votes that would bring the process perilously close to the June 5 deadline.