They aren't natural allies, given their backgrounds.
McConnell is a soft-spoken, inside player who is known to use his extensive knowledge of Senate rules to achieve his aims. A Kentucky resident since he was 13, he's spent his professional life in politics. He worked as a Capitol Hill intern and aide before first winning his Senate seat in 1984. For many years, McConnell touted the federal monies he was able to direct back to Kentucky from his perch on the Appropriations Committee as a reason for re-election — a practice the tea party opposes as wasteful spending.
Paul hails from a political family known for challenging the establishment — his father, former Rep. Ron Paul of Texas, ran for president in 1988 as the Libertarian Party candidate, then pushed his limited-government agenda in seeking the White House as a Republican in 2008 and 2012.
The younger Paul moved to Kentucky after graduating from Durham, N.C.-based Duke University's medical school and spent 17 years as a practicing opthamologist. He began his career in state politics in the early 1990s when he founded an anti-tax group called Kentucky Taxpayers United.
Paul's alliance with McConnell gives him access to wealthy donors who are usually essential to mounting a national campaign. Paul's father was supported in his Republican presidential bids almost exclusively by small donors.
"Senator McConnell taps into a big money base that is not going to tend to gravitate toward Senator Paul because they're primarily made up of people who don't want government to be smaller," said David Adams, who managed Paul's campaign during the 2010 Senate primary.
Five days after he praised Paul's filibuster, McConnell emailed supporters urging them to donate to his Senate re- election campaign and to sign a petition declaring that they too "stand with Rand and Mitch."