"If he chose to run, he would be the most creditable candidate for president since Henry Clay," McConnell said, according to the Huffington Post.
Henry Clay, known for brokering multiple compromises during his time representing Kentucky in Congress, ran for president three times— in 1824, 1832, and 1844 — but never won.
McConnell and Paul were not always buddies. McConnell tried to prevent Paul from winning the Republican nomination in the 2010 Senate race, but the two have developed a supportive professional relationship since then.
Paul is popular in Kentucky, and his endorsement of McConnell could give the Minority Leader a real boost.
Paul, however, has struggled to explain why he's supporting McConnell in 2014.
"Uhh, because he asked me," Paul said when asked by Glenn Beck about the endorsement in February. "He asked me when there was nobody else in the race. And I said yes."