McConnell announced his support on the Senate floor moments after the lame-duck session of Congress began, The Washington Post reported.
Sen. Jim DeMint, R-S.C., indicated he would offer a resolution to the Senate Republican Conference this week -- possibly as soon as Tuesday -- to adopt a moratorium on earmarks.
"Make no mistake, I know the good that has come from the projects I have helped support throughout my state. I don't apologize for them," McConnell said from the floor. "But there is simply no doubt that the abuse of this practice has caused Americans to view it as a symbol of the waste and the out-of-control spending that every Republican in Washington is determined to fight. And unless people like me show the American people that we're willing to follow through on small or even symbolic things, we risk losing them on our broader efforts to cut spending and rein in government."
President Barack Obama said he welcomes McConnell joining the bipartisan effort to crack down on wasteful spending "which we can't afford during these tough economic times."
"As a senator, I helped eliminate anonymous earmarks, and as president, I've called for new limitations on earmarks and set new, higher standards of transparency and accountability," Obama said in a statement issued by the White House. "But we can't stop with earmarks as they represent only part of the problem. In the days and weeks to come, I look forward to working with Democrats and Republicans to not only end earmark spending, but to find other ways to bring down our deficits for our children."
Republicans take control of the House of Representatives in January, leaving Obama and congressional Democrats with less leverage to shape the legislative agenda.
Since public disclosure of earmark requests began three years ago, McConnell sought nearly $1 trillion worth of earmarks, mostly benefiting the Bluegrass State, the Taxpayers for Common Sense told the Post.
Sen. Tom Coburn, R-Okla., said Republican opponents of the earmark ban should watch their backs in the 2012 party primaries.
Coburn put his GOP colleagues on notice that if they don't support a moratorium, they "sure should" expect primary competition, The Hill reported.
"Republicans can send a signal that they get it," Coburn said in an interview with the conservative magazine The Weekly Standard. "Or they can send a signal that they continue to not get it and say they're not going to change. And if they do that, they're going to pay for it at the ballot box."