Evan McMorris-Santoro July 7, 2010, 2:26 PM

Senate Minority Leader Mitch McConnell backed the wrong horse in the Senate primary back home in Kentucky and now he’s paying the price with state Republicans. A new PPP (D) poll out today shows McConnell’s approval rating has fallen to a record low 34% in his home state.

Even worse for McConnell is that only 38% of voters surveyed said that they want McConnell to remain the head of his party’s caucus in the Senate. Almost half — 49% — said they don’t think McConnell should keep his job as Republican leader.

The slide in approval for McConnell was almost entirely the result of voters he upset when he backed state Attorney General Trey Grayson over the eventual nominee (and tea party favorite) Rand Paul in the Republican Senate primary. McConnell’s support among Democrats and even moderate Republicans has stayed level for the past three months. But it’s seen a precipitous decline among conservatives.

PPP reports on the internals of the McConnell support numbers:

His 23% approval rating with moderates is unchanged from two months ago and his 15% standing with liberals is actually slightly improved from 12% in the May poll. But with conservatives, who comprise the largest voting bloc in Kentucky, he’s fallen from 47% all the way down to 27%.

Though Rand Paul himself has made efforts to make nice with McConnell — whom he attacked repeatedly during the primary — it appears Paul’s supporters have not. As long as he remains one of the most prominent examples of the Republican establishment in Washington, it seems that McConnell — who just survived a (relatively) tough reelection campaign in 2008 — will continue to have a big problem back home in Kentucky.

Mitch McConnell