Updated

Senate Minority Leader Mitch McConnell easily defeated a Tea Party challenge in Tuesday's GOP primary to keep his Kentucky Senate seat and now faces a November race that is emerging as the toughest in his five-term career.

The Associated Press called the race for McConnell over his Tea Party-backed challenger, Louisville businessman Matt Bevin, minutes after the polls closed.

As an experienced campaigner with a huge war chest, McConnell was able to fend off Bevin’s strong, early challenges, closing the race in the final months with a double-digit lead that he rode to victory.

"He made me a better candidate," McConnell in his victory speech said of Bevin. "Send me back to Washington and Kentucky will always have a champion in the Capitol."

Bevin spent $3.3 million in the failed bid, and had financial support from such outside conservative groups as the Senate Conservatives Fund and FreedomWorks.

He tried to characterized himself as the true conservative in the race. But Bevin's campaign stumbled early when a document surfaced from his investment company calling the bailout a "positive development." And Bevin was caught on tape telling a crowd at a pro-cockfighting rally that he thought it was wrong to make cockfighting illegal.

McConnell used high-profile endorsements from the U.S. Chamber of Commerce and the National Rifle Association to tout his conservative bona fides.

At present, every poll has McConnell’s race against Alison Lundergan Grimes, Kentucky’s secretary of state, as a dead heat with Election Day just six months away.

Grimes also easily won her Tuesday primary.

Her race with McConnell also is expected to be the most expensive congressional race this election cycle, as Republicans try to win a net six seats to take control of the upper chamber. If that happened, McConnell would replace Nevada's Democratic Sen. Harry Reid as the Senate majority leader.

Both candidates already have spent millions yet still have cash remaining --- roughly $10 million for McConnell and $5 million for Grimes. Much of the money is coming from interests outside the state -- including Hollywood money eager to knock off the top Senate Republican and McConnell supporters trying to stop what they in part consider overspending by the Obama administration, including ObamaCare.

"My opponent is in this race because Barack Obama and Harry Reid want her to be," McConnell also said after his win. "There's a reason Hollywood liberals are sending her checks ... There isn't a dime's difference between her and Harry Reid."

McConnell and Grimes have raised a combined $19 million in the two years leading up to their primaries.

McConnell and his allies are already running television ads comparing Grimes to Obama, whose disapproval rating in Kentucky is at least 60 percent.

This week, two of the support groups -- Kentuckians for Strong Leadership and the Kentucky Opportunity Coalition – put down a combined $5.2 million for general election ad time.

Conservatives are unhappy about McConnell's compromises with Democrats to raise the debt ceiling, pass the Wall Street bailouts and other fiscal issues.

"I think he'll have a very tough time bringing them back," Grimes campaign manager Jonathan Hurst said earlier this week. "We will welcome those who vote against Sen. McConnell and his own party on Tuesday to join our campaign."

Josh Holmes, a McConnell campaign adviser, said the primary gives McConnell's camp an advantage by forcing it to get the campaign running early.

"Our campaign has been up and running at full speed for six months," Holmes said. "We are able to get through the primary election with an operation that we feel confident about that we are able to test and we're able to carry into the fall that has some success already under its belt."

The Associated Press contributed to this report.