Voters in Alabama will head to the polls Aug. 15 to pick a Republican nominee for U.S. Senate.

And Mitch McConnell will be nervously watching the results.

His leadership PAC, and his allies, are pouring millions into the race to support appointed Senator Luther Strange, as he faces two stalwart conservatives.

One is former State Supreme Court Justice Roy Moore.  The other is Congressman Mo Brooks, who is already calling on McConnell to step aside as Majority Leader.

POLITICO reports:

The Republican leader is aiming to thwart Rep. Mo Brooks and former state Supreme Court Chief Justice Roy Moore in a special election in Alabama next month. Both men are campaigning against McConnell as a despised symbol of the establishment — and both would exacerbate his already stiff challenge wrangling his GOP Conference.

McConnell is responding in kind. His super PAC is set to spend as much as $8 million to boost his favored candidate, recently appointed Republican Sen. Luther Strange. McConnell has activated his sprawling donor network and pressed the White House for more resources. And the National Republican Senatorial Committee, the Senate GOP campaign arm McConnell controls, has warned consultants they’ll be cut off from future work if they assist Strange’s opponents.

And McConnell has reason to be worried.

While the Senate has always had members with strong conservative voting records, conservative leadership had been waning since the retirement of North Carolina’s Jesse Helms.

But the arrivals of Rand Paul, Mike Lee and Ted Cruz have not only reinvigorated Senate conservatism, but presented a challenge to the normally-unchallenged moderate Republican leadership.

Mo Brooks would only add to McConnell’s headaches.

With an “A” rating from Gun Owners of America, and a 92% conservative voting record from the American Conservative Union, Brooks is waging war against McConnell personally.

“Inside the Republican conference, Mitch McConnell’s got to go,” Brooks told a stunned crowd at a breakfast event hosted by the Heritage Foundation. “Absolutely, he is the head of the swamp in the United States Senate.”

That surprised many in Washington.  In the House, Brooks was a supporter of then-Speaker John Boehner, voting against attempts to replace him.

It’s a sign of just how unpopular McConnell has become with Republican voters.

Also challenging Brooks and Strange for a spot in a likely runoff is former Alabama State Supreme Court Justice Roy Moore — a conservative stalwart for over 20 years.

Moore is best known for his standoff with the U.S. Justice Department over the erection of a Ten Commandments monument on state grounds.

Anti-religion extremists sued Alabama to force its removal, claiming it constituted the establishment of Christianity as the officially-recognized state religion, though both Christianity and Judaism recognize the Commandments, and the monument neither compelled nor denied any religious exercise.

The monument was hauled away in 2004 and Moore was removed from the Court for refusing to obey a court’s order to remove it.

He returned to the Court in 2013 after winning the statewide race for Chief Justice, until he was forcibly removed from the Court again, this time for refusing to recognize same-sex marriages.

Moore vows, if elected to the Senate, he will fight to remove McConnell as Majority Leader, warning McConnell, “I’m impossible to manage.”

With Brooks, Moore and Strange crowding the top of the ticket in the Aug. 15 primary, a Sept. 26 runoff is almost certain.

With Brooks and Moore splitting the conservative vote, the likeliest scenario is Strange finishing first, but short of the 50 percent needed to avoid a runoff.

That leaves Brooks and Moore fighting each other for the opportunity to face Strange in the runoff.

McConnell hopes his millions will boost Strange going into the runoff, or avoid his personal nightmare, Strange slipping to third and leaving the Republican nomination — and almost certainly a United States Senate seat, to either Brooks or Moore.