Senate Minority Leader Mitch McConnell quelled an intraparty fight Monday when he reluctantly embraced an earmark ban demanded by the GOP’s conservative wing.

In a surprise floor speech, the Kentucky Republican said that he was joining “the Republican leadership in the House in supporting a ban on earmarks,” despite his continued belief that earmarking is a Constitutional right of lawmakers and a necessary practice.

“I’m not wild about turning over more spending authority to the executive branch,” he said Monday. But the “only way we will be able to turn the corner and save our future is if elected leaders like me make the kinds of difficult decisions voters are clearly asking us to make.”

By agreeing to support a ban on earmarks, McConnell, a longtime appropriator, at least temporarily put off a showdown with Sen. Jim DeMint (R-S.C.), the conservative agitator who has led the charge for a ban. McConnell’s move, combined with the White House’s announcement Monday of its support for a temporary earmark ban, may put more pressure on Senate Democrats to address the issue, too.

“This was just becoming a distraction,” a senior GOP aide said, explaining McConnell’s announcement. The aide added that today’s planned closed-door vote on the ban was shaping up to be an ugly fight between traditional legislators in the Conference and the increasingly large faction of conservative reformers.

“McConnell listened, and he’s reflecting the will of the caucus on this, and it’s going to make everything a lot easier,” the aide said.

While McConnell’s speech did not directly address the internal politics of his Conference, he acknowledged that the public was on the side of reformers. He argued that Democrats were on the losing end of the elections this year in part because they ignored the public. “When it comes to earmarks, I won’t be guilty of the same thing,” he said.

As lawmakers made their way back to Washington, D.C., on Monday, it appeared as if DeMint and McConnell would find themselves in a battle over who has the most sway within their Conference.

Although DeMint has lined up the support of Republican Policy Committee Chairman John Thune (S.D.), most of the incoming freshman class and other conservatives, opponents of the ban — led by Sen. James Inhofe (Okla.) — still appeared to make up roughly half of the Conference.

During a tea party rally organized by Americans for Prosperity to show support for the ban, DeMint warned his colleagues that, “if the Senate Republicans fail to pass a ban on earmarks tomorrow, [then] obviously they have not gotten the message.”

Although McConnell has not been whipping the vote outright, he has made clear in private conversations with Senate Republicans that he favored earmarks. “There’s a lot of pressure on them to cave in,” DeMint said to the dismay of the gathered activists.

Over the past several years, DeMint has had an increasingly antagonistic relationship with his own leaders, often criticizing their decisions and forcing nasty floor fights in his crusade against earmarks.

The South Carolina upstart also put his leadership on notice last year when he used his Senate Conservatives Fund as a platform to back strongly conservative candidates in GOP primaries that he could count on as a base of support within the Conference.

DeMint’s efforts have rubbed many of his colleagues the wrong way, and following the defeat of tea party favorites Sharron Angle and Christine O’Donnell in Nevada and Delaware, Republicans accused DeMint of essentially sabotaging the GOP’s efforts to take control of the Senate.

While McConnell pointedly refused to even mention DeMint in his floor speech Monday — giving credit instead to House Republicans rather than to DeMint — GOPers quickly sought to demonstrate their unity following his endorsement.

“Sen. McConnell’s support for the earmark moratorium demonstrates the kind of bold leadership our party needs,” DeMint said in a statement.

“His statement today and tomorrow’s vote to enact the moratorium will send a clear signal to voters that Republicans heard the message of the last election. I am proud that House and Senate Republicans have united to end the earmark favor factory,” he added.

House Minority Leader John Boehner also hailed McConnell’s decision.

“House and Senate Republican leaders are listening to the American people, and are united in support of an earmark ban,” the Ohio Republican said in a statement. “An earmark moratorium shows that elected officials are serious about restoring trust between the American people and those who are elected to represent them.”

Many Senate Democrats don’t seem to feel the same pressure to forgo their power of the purse through earmarks.

While earmarks are expected to come up today during their weekly luncheon, the idea of an earmark ban received a cool reception from many in the Conference.

“I love that the guys who talk about earmarks are usually calling the departments saying, ‘I didn’t put in an earmark, but before you send somebody up for confirmation,’” these projects must get funding, Senate Judiciary Chairman Patrick Leahy (D-Vt.) said with a shake of his head.

Similarly, Sen. Bill Nelson on Monday rejected the idea that earmarks should be banned. “No, it’s self-evident” that they should still be available, the Florida Democrat said, arguing that “when it’s for national security, when its for big jobs” projects, lawmakers should have the right to seek earmarks.

And Regan Lachapelle, spokeswoman for Senate Majority Leader Harry Reid (Nev.), also threw cold water on the idea of a full earmark ban. “It is up to each Senator whether or not they will support Congressionally directed funding to their state,” she said.

But at least two Democrats, Sens. Mark Udall (Colo.) and Claire McCaskill (Mo.), hailed the GOP’s decision.

“I welcome Senator McConnell to the fight to ban earmarks,” McCaskill said in a statement. McCaskill is up for re-election in 2012. “Tax dollars are always best distributed based on merit. I’m glad that Republican leadership is coming around to this idea; now it’s my Democratic colleagues’ turn to get on board.”

Jackie Kucinich contributed to this report.