WASHINGTON (Reuters) - A measure to extend the U.S. debt limit for nearly four months moved closer on Tuesday to a vote and the White House said the president would sign the bill if it cleared Congress, easing uncertainty that could have threatened the U.S. economy.

The debt limit "suspension," which would allow the government to borrow money until May 19, is due to come to a vote in the Republican-controlled House of Representatives on Wednesday without amendments.

House Rules Committee Chairman Pete Sessions of Texas said he believed the measure would achieve "near unanimous support" from the House Republican caucus, which would guarantee its passage.

President Barack Obama "would not stand in the way of the bill becoming law," White House spokesman Jay Carney said earlier at a briefing. Democratic Senate Majority Leader Harry Reid has similarly expressed approval.

The administration and some Democrats made clear on Tuesday they would prefer a longer-term reprieve from having again to seek an expansion of the nation's borrowing capacity. But the White House welcomed movement on the contentious issue, which has financial markets worried about a self-engineered U.S. debt default.

"What happened ... was a very significant development in terms of de-escalating the sense of conflict over this," Carney said.

Even a sermon delivered at a traditional prayer service at Washington's National Cathedral a day after Obama's inauguration cited the clash over the debt limit as a strain on the nation's spirit.

Reverend Adam Hamilton, a Methodist pastor from Leawood, Kansas, told the attendees, which included Obama, that "to many Americans we seem like a house divided that cannot stand" because of political bickering and discord over issues like the national debt ceiling and healthcare.

Hamilton likened the partisan rancor in Washington to the Old Testament friction between Moses and his people as he led them out of Egypt.

REPUBLICANS FALL IN LINE

The United States is on track to run out of room under its congressionally-imposed borrowing limit of $16.4 trillion sometime between mid-February and early March, and a vote to suspend the debt ceiling would take the prospect of default off the table at least temporarily.

"I'm glad we are not facing a crisis here in a matter of a few days," Reid of Nevada said.

As the debt limit bill moved through Congress on Tuesday, some lawmakers expressed concern the short-term nature of the measure would not calm jittery financial markets. The conservative group FreedomWorks urged lawmakers to oppose it, saying it failed to cut spending.

But another conservative group, Club for Growth, said it would not oppose the measure but instead save its energy to push for spending cuts and limits to government growth in the remaining budget debates.

Congressional Republicans have in the past balked at raising the debt cap without securing matching or greater spending cuts in exchange, and have raised the specter of default as a bargaining chip.

But they backed down from that stance at a policy retreat last week, preferring to shift the focus of budget battles with the White House to a March 1 date for automatic deep spending cuts and a March 27 expiration of funding for government agencies and programs.

Instead of making budget cuts a precondition for expanding U.S. borrowing authority, the Republican bill would require both the House and Senate to pass budgets by April 15, on pain of having members' paychecks withheld should they fail to do so.

The White House cautioned that an extension only would push a debt ceiling crisis into the not-too-distant future.

"A temporary solution is not enough to remove the threat of default that Republicans in the Congress have held over the economy," the White House's budget office said in a statement.

Republicans, even those who have chafed under the leadership of Speaker John Boehner, fell in line behind the debt ceiling extension.

"I am actually okay with what leadership is doing right now," said Idaho Representative Raul Labrador, who was one of the 12 conservative House members who tried to oust Boehner as the House leader in early January.