McConnell is likely to face Kentucky Secretary of State Alison Lundergan Grimes, Democrats' top remaining recruit, in 2014. Lundergan Grimes announced her bid last week. Her father, Jerry Lundergan, is a well-connected former party chairman, and the family is close friends with the Clintons.
But he's been building an operation for months now, and has so far raised $15.4 million for the cycle. If he keeps up this fundraising pace, he could exceed the $21 million he raised for his 2008 race, which he won by 6 percentage points.
President Obama is deeply unpopular in the red-leaning state, losing Kentucky by more than 20 points in 2012.
Lundergan Grimes is not required to report her fundraising until October, after the close of the third quarter.