Sen. Jim DeMint has endorsed Rand PaulRand PaulGOP healthcare plans push health savings account expansion Congress must reform civil asset forfeiture laws ­ObamaCare fix hinges on Medicaid clash in Senate MORE in Kentucky’s Senate GOP primary race, putting him at odds with Senate Republican Leader Mitch McConnellMitch McConnellPoll: Senate should confirm Gorsuch Cardboard cutouts take place of absent lawmakers at town halls GOP groups ramp up pressure on lawmakers over ObamaCare MORE.

DeMint (R-S.C.) announced Wednesday he would support Paul, an eye surgeon who is the son of Rep. Ron Paul (R-Texas), through his Senate Conservatives Fund, which has raised hundreds of thousands of dollars for conservative candidate Marco RubioMarco RubioA guide to the committees: Senate Schumer: GOP will break from Trump within months GOP loses top Senate contenders MORE in Florida.

DeMint’s move will be seen by some Senate Republicans as a breach of protocol because he is stepping onto McConnell’s home turf to support a candidate McConnell does not.

McConnell on Tuesday formally endorsed Paul’s opponent, Kentucky Secretary of State Trey Grayson.

“I rarely endorse in primaries, but these are critical times,” McConnell said in a television ad for Grayson.

DeMint said in a statement that he's not trying to undermine McConnell.

"Senator McConnell and I are on different sides in this race, but I support him as our leader," DeMint said.

DeMint touted Paul as a strong advocate for balanced budgets, an opponent of Washington’s culture of spending earmarks and a supporter of term limits.

"I'm endorsing Rand Paul because he's a true conservative who will stand up to the Washington establishment," DeMint said. "Rand has been running on the issues that matter since the beginning of this campaign.

“He's not a career politician, and he's got the guts to stand up to the massive spending, bailouts, and debt that are being forced on us in Washington,” DeMint added.