Updated

Tennessee Republican Sen. Lamar Alexander easily defeated a group of GOP challengers on Thursday to clinch his party’s nomination in the November general election.

The incumbent senator’s most prominent challenger was Tea Party-backed state Rep. Joe Carr, who had hoped voter anger over issues such as the immigration crisis would make up for his vast disadvantage in fundraising. Alexander outspent Carr by a ratio of five-to-one.

With 99 percent of precincts reporting, Alexander had 50 percent of the vote, compared with 41 percent for Carr and 5 percent for Memphis radio station owner George Flinn.

Meanwhile, scandal-plagued Republican Rep. Scott DesJarlais was neck-and-neck with his primary challenger state senator Jim Tracy in Tennessee's 4th District. With 100 percent of precincts reporting, DesJarlais led Tracy by less than 40 votes and the Associated Press had deemed the race too close to call.

DesJarlais, a physician, won re-election in 2012 despite revelations he urged a patient he was dating to seek an abortion. After the election, court officials released transcripts of divorce proceedings that included DesJarlais admitting under oath that he had eight affairs and used a gun to intimidate his first wife.

In his victory speech Thursday night, Alexander called for compromise in Washington. Alexander is strongly favored to win re-election in November in heavily Republican Tennessee.

"If we want to change ObamaCare, we're going to have to pass something. If we want to fix the debt, we're going to have to pass something," Alexander said. "And to do that we're going to have to work with other people to get it done."

Known on Capitol Hill as one of the more moderate members of his party, Alexander has been in the political player in Tennessee for the last four decades, serving two terms as governor and two terms in the U.S. Senate. He also unsuccessfully ran for president twice.

The 74-year-old was painted by his main challengers, Carr and Flinn, as a candidate too focused on national politics and out of touch with constituents back home.

It’s a strategy that has worked before this election cycle. Earlier this year, then-House Majority Leader Eric Cantor was unexpectedly defeated in the Virginia GOP primary by Dave Brat, an economics professor at a small private college in the state.

Cantor, who held the second most powerful GOP position in the House, was largely brought down on the message he had lost touch with Virginia voters.

Carr, like Brat, campaigned heavily on immigration. In particular, Carr emphasized that he opposed the Alexander-backed immigration compromise legislation of 2013.

However, Alexander was careful to avoid a Cantor-like upset and spent the last few weeks crisscrossing Tennessee to meet with voters.

Carr thanked his supporters in a speech Thursday night, calling them his "extended family" and vowing to continue to advance the causes he campaigned on.

“While this battle was lost tonight, this isn’t the most important battle, it wasn’t the first battle and it won't be the last battle," he said. "Because what we are fighting for is the heart and soul of America”

Meanwhile, Democratic Rep. Steve Cohen fended off his primary challenger as he seeks a fifth consecutive term in the House seat representing Tennessee's 9th District.

Cohen, a white and Jewish Memphis native, once again defeated an African American challenger in a majority African American district.

His challenger Ricky Wilkins, an attorney, had sought to highlight ethnic and racial differences between Cohen and his constituents in the district, which Cohen has represented since 2006.

In the 3rd District, incumbent Republican Rep. Chuck Fleischmann claimed victory in a tight race over Weston Wamp. Wamp is the son of former Rep. Zach Wamp, Fleischmann's predecessor in the House.

Fox News’ Chris Stirewalt and The Associated Press contributed to this report