Senate Republican Leader Mitch McConnellAddison (Mitch) Mitchell McConnellSenate passes 0B defense bill Overnight Health Care: New GOP ObamaCare repeal bill gains momentum Overnight Finance: CBO to release limited analysis of ObamaCare repeal bill | DOJ investigates Equifax stock sales | House weighs tougher rules for banks dealing with North Korea MORE (Ky.) said Tuesday he supports Mitt Romney's bid to win the Republican presidential nomination.

"I support Mitt Romney for president of the United States," McConnell said.

He predicted Romney would be the nominee and said the GOP is unifying behind his campaign.

McConnell's announcement came hours after House Speaker John BoehnerJohn Andrew BoehnerSpeculation mounts, but Ryan’s job seen as safe Boehner warns Trump: Don't pull out of Korea-US trade deal GOP Rep: Ryan wasting taxpayers dollars by blocking war authorization debate MORE (R-Ohio) said he would back Romney. The former Massachusetts governor has been lining up party leaders and establishment Republicans behind his bid, particularly after rival Rick Santorum exited the presidential campaign.

"We're all looking forward to the fall campaign, which is already under way," McConnell said.

McConnell cited a recent tracking poll showing Romney ahead of President Obama by a few points in a hypothetical match-up.

The GOP leader urged his party to unify behind Romney during a television appearance earlier this month.

Romney still faces Newt Gingrich and Ron Paul in the primary process, but the two of them are unlikely to catch up to him the delegate count, leaving Romney the likely nominee.