Some House Republican hardliners were already pushing back at Johnson's proposal for a two-step stopgap bill that would not otherwise cut spending, a "clean" bill of the kind that led to the historic ouster of Johnson's predecessor, Kevin McCarthy.

This is the third fiscal showdown in Washington this year, following a months-long spring standoff over the nation's more-than-$31 trillion in debt, which brought the federal government to the brink of default.

The ongoing partisan gridlock, accentuated by fractures within the narrow 221-212 House Republican majority, led Moody's late on Friday to lower its credit rating outlook on the U.S. to "negative" from stable, as it noted that high interest rates would continue to drive borrowing costs higher. The nation's deficit hit $1.695 trillion in the fiscal year ended Sept. 30.

Some congressional Democrats indicated they were open to Johnson's plan, which would need to pass the Democratic-majority Senate and be signed into law by President Joe Biden by midnight on Friday to avoid disrupting pay for up to 4 million federal workers, shuttering national parks and hobbling everything from financial oversight to scientific research.

"I am committed to returning Washington to regular order, but you can't fix a decades-old broken system in a matter of weeks," Johnson, a Louisiana lawmaker who never before held a senior leadership position in Congress, said on social media on Sunday.

Johnson unveiled the unusual two-step continuing resolution, or "CR," on Saturday. It seemed geared to find support from two warring Republican factions: hardliners who wanted different funding deadlines for different federal agencies and centrists who called for a "clean" vehicle without spending cuts or conservative policy riders that Democrats would reject.

His bill would extend funding for military construction, veterans benefits, transportation, housing, urban development, agriculture, the Food and Drug Administration and energy and water programs through Jan. 19. Funding for all other federal operations - including defense - would expire on Feb. 2.

The bill is intended to pressure the House and Senate to agree on spending bills for fiscal 2024 by the assigned dates. Johnson also warned Democrats that House Republicans would impose a full-year CR for 2024 "with appropriate adjustments to meet our national security priorities" if Congress fails to reach agreement.

The approach quickly came under fire from the White House and members of both parties, including hardliners who had lobbied for a CR with spending cuts. Firebrand Republican Representative Marjorie Taylor Greene said she intended to vote against it, as did hardline colleague Warren Davidson.

DEMOCRATS 'WILLING TO LISTEN'

The White House over the weekend blasted the plan as chaotic, but there were also indications that it could provide a path forward for Congress, given the absence of cuts and Johnson's decision to assign defense spending to the latter end-date. Democrats had worried that Republicans would put defense and other party priorities in the first tranche and then threaten to let the remaining programs shut down.

"It's a good thing the Speaker didn't include unnecessary cuts and kept defense funding with the second group of programs," a Senate Democratic leadership aide said.

Democratic Senator Chris Murphy told NBC on Sunday that he could support the two-step model.

"It looks gimmicky to me," Murphy said. "I don't like what the House is talking about, but I'm willing to listen."

House Republicans are aiming for a Tuesday vote. But it is unclear whether their conference, which has spent the past 10 months at war with itself over spending and culture war issues, can muster the 217 votes needed to pass the measure without Democratic support, which many Republicans view as the benchmark of success.

Failure to hit that benchmark led to McCarthy's ouster, but some House Republicans suggested Johnson deserved more time.

"What he needs is the support of every member of our conference, and he deserves that. Now people need to suck it up and do some things they may not like but that he needs done to be successful," said Representative Tom Cole, chair of the House Rules Committee, which will hold a Monday hearing on the new CR.

The brutal infighting that has characterized Republicans this year, including the party's own rejection of three seasoned nominees for House speaker, coincides with falling federal revenues and mounting costs for interest, health and pension outlays.

FRACTION OF THE BUDGET

Lawmakers are at odds over discretionary spending for fiscal 2024. Democrats and many Republicans want to stick to the $1.59 trillion level that Biden and McCarthy set in their debt ceiling agreement earlier this year. Hardliners have pushed for a figure $120 billion lower. But in recent days, they have signaled a net willingness to compromise.

The political fracas is focused on just a fraction of the total U.S. budget, which also includes mandatory outlays for Social Security and Medicare. Total U.S. spending topped $6.1 trillion in fiscal 2023.

Republicans believe Johnson, a Christian conservative who for now commands the respect of hardliners, is unlikely to risk the same fate as McCarthy if he ultimately averts a partial shutdown with substantial House Democratic support.

"We all learned a lesson," said Representative Ken Buck, one of eight Republicans who voted to oust McCarthy on a parliamentary motion to "vacate the chair."

(Reporting by David Morgan; Editing by Scott Malone and Andrea Ricci)

By David Morgan