Just hours after House Speaker John Boehnerpresumptive Republican presidential nominee Mitt Romney, Mitch McConnell, the Senate Minority Leader from Kentucky, added his own endorsement to the pile.
McConnell, speaking to reporters Tuesday, said "we're all behind" Romney.
"I support Governor Romney for President of the United States and he is going to be the nominee," he said. "If you've noticed, the party is in the process of unifying behind him. And I think it's going to be an incredibly close, hard fought race."
He added: "I think it's going to be a very, very competitive election. We're all behind him and looking forward to the fall campaign, which is actually already underway."
Romney has accumulated an increasing number of endorsements from members of the Republican establishment in recent weeks, particularly in light of Rick Santorum's recent exit from the race. As high-profile Republicans fall in line behind the candidate, the perception is that Romney will finally benefit from the full backing of the party.
Earlier Tuesday, Boehner said "it's clear now that Mitt Romney is going to be our nominee" and that he would be "proud to support Mitt Romney and do everything I can to help him win."
Romney still faces two Republican competitors in the GOP field - Newt Gingrich and Ron Paul - but few expect either of those candidates to impede Romney further in his pursuit of the GOP nomination. According to CBS News estimates, Romney leads Gingrich in the delegate count by more than 500. He leads Paul by exactly 600, according to the same estimate.
Ben Wagner contributed to this report.