Democratic Senate Majority Leader Harry Reid reported progress Monday toward a deal to avoid a threatened default and end a two-week partial government shutdown as President Barack Obama called congressional leaders to the White House to press for an end to the impasse.

"We're getting closer," Reid told reporters after he met privately with the Republican leader, Sen. Mitch McConnell.

While Reid said there was not yet an accord, he said he hoped to have a proposal to outline when the two men and House of Representatives leaders meet with Obama at mid-afternoon. No details were available on the terms under discussion.

Speaking to reporters at a Washington charity, Obama said, "My hope is that a spirit of cooperation will move us forward over the next few hours."

Otherwise, he warned that the threat of default was legitimate.

"If we don't start making some real progress both in the House and the Senate, and if Republicans aren't willing to set aside some of their partisan concerns in order to do what's right for the country, we stand a good chance of defaulting," he said.

At issue are two normally routine pieces of legislation that have become entangled in disputes over Obama's health care overhaul and overall government spending. Congress' failure to pass a bill temporarily funding the government led to the partial shutdown on Oct. 1, the first in 17 years. And if Congress doesn't approve a separate measure increasing the debt ceiling _ the amount of money the government is allowed to borrow _ the Obama administration says it will not be able to pay its bills, risking default.

The two Senate leaders, Reid and McConnell, had spoken by phone Sunday but failed to agree on a deal to raise the nation's borrowing authority above the $16.7 trillion debt limit or reopen the government. Congress is racing the clock with Treasury Secretary Jack Lew warning that the U.S. will quickly exhaust its ability to pay the bills on Thursday.

Reid and McConnell _ veteran senators hardened by several budget disputes and years of negotiations _ are at an impasse over yet another source of fiscal fighting: the automatic, across-the-board spending cuts known as sequestration and whether to undo or change them as part of a budget deal. Democrats are pressing for a higher amount of spending, while Republicans want to keep the spending at the deficit-cutting level of the 2011 law, the result of that year's high-stakes budget battle.

McConnell insisted a solution was readily available as he embraced the proposal from a bipartisan group of 12 senators, led by Collins and Manchin, that would re-open the government and fund it at current levels for six months while raising the debt limit through Jan. 31. It also would give agencies greater flexibility in dealing with the automatic budget cuts, delay the medical device tax for two years and establish income verification for individuals receiving subsidies to buy health insurance.

Separately, a bipartisan group led by Republican Sen. Susan Collins met for two hours Monday morning on a possible solution to the impasse.

"We're making very good progress, but there's still many details to be worked out," Collins said before joining her Republican colleagues at a meeting with McConnell. "We don't have a finished, agreed-upon product yet but I think we had an excellent meeting. And we'll get together later today."

Unclear was whether any Senate deal would pass the Republican-controlled House by Thursday, though Senate Democrats were hoping momentum and an imminent default would pressure House lawmakers.

There was no certainty that the growing anxiety among financial leaders around the world would provide the necessary jolt to Senate leaders, who represent the last, best chance for a resolution after talks between President Barack Obama and House Republican leaders collapsed.

Democratic Sen. Joe Manchin said Monday that investors are growing increasingly "skittish" about the possibility of default. The bond markets were closed for a holiday, and by mid-morning the stock market was down modestly, with both the Dow Jones industrial average and Standard & Poor's 500 index losing less than 1 percent. Trading in Asia was muted, with markets in Tokyo and Hong Kong closed for holidays.

Christine Lagarde, the International Monetary Fund's managing director, spoke fearfully about the disruption and uncertainty, warning on Sunday of a "risk of tipping, yet again, into recession" after the fitful recovery from 2008.

The shutdown has furloughed 350,000 federal workers, impeded various government services, put continued operations of the federal courts in doubt and stopped the IRS from processing tax refunds. Some parks and monuments remain closed, drawing a protest at the National World War II Memorial on Sunday that included tea party-backed lawmakers who had unsuccessfully demanded defunding of Obama's 3-year-old health care law in exchange for keeping the government open.

Sen. Bob Corker, a Republican, said the leaders of both parties need to be "getting on the same page."

Politically, Republicans are reeling, bearing a substantial amount of the blame for the government shutdown and stalemate.

"We're in a free-fall as Republicans, but Democrats are not far behind," said Sen. Lindsey Graham in warning Democrats about seizing on the bruised Republican brand as leverage to win more concessions.

McConnell and Republicans want to continue current spending at $986.7 billion and leave untouched the new round of automatic cuts on Jan. 15 that would reduce the amount to $967 billion. Democrats want to figure out a way to undo the reductions, plus a long-term extension of the debt limit increase and a short-term spending bill to reopen the government.