Republican Mike Braun will defeat Democratic Sen. Joe Donnelly in Indiana, CNN projects, giving Republicans a major pick-up to bolster their Senate majority in a state President Donald Trump won handily two years earlier.
First elected to the Senate in 2012, Donnelly spent his first six years aware he'd be among the top Republican targets in his bid for re-election.
Donnelly had won the seat in 2012 with a healthy dose of luck, following a series of Republican errors. A tea party primary had purged six-term Republican Sen. Richard Lugar, replacing him on the ballot with controversial state treasurer Richard Mourdock. Then, Mourdock stumbled just two weeks from Election Day, calling pregnancies resulting from rape "something that God intended to happen" -- a comment that led then-presidential nominee Mitt Romney to distance himself from Mourdock and all but cemented Donnelly's victory.
Trump's 19 percentage point victory in Indiana underscored just how difficult the state would be for a Democrat to hold in 2018.
And two Republican congressmen, Todd Rokita and Luke Messer, spent years angling to run against Donnelly.
But Braun, a little-known former state representative and owner of an auto parts distributorship with millions of his own dollars to spend, ran a masterful primary campaign. He offered himself as a straight-talking alternative and cast Messer and Rokita as ambitious politicians who even looked alike. For a television ad, he carried around cardboard cutouts of the two and asked voters if they knew which one was which.
Outspending both of his opponents, Braun won the primary.
The general election turned into a battle over trade, with both candidates accusing the other of outsourcing jobs and wages.
Republicans attempted to brand Donnelly as "Mexico Joe" after The Associated Press reported that Donnelly owned stock in a business that had a factory in Mexico. Donnelly sold the stock. Braun, meanwhile, was attacked for sourcing many of the auto parts his business sells from China.
Trump and Vice President Mike Pence, the former Indiana governor, each made several visits to the state to campaign for Braun. Trump branded Donnelly "Sleepy Joe."
Donnelly sought to portray himself as a centrist, often praising Trump and highlighting moments at which he had broken from Democratic leadership in the Senate.
Braun, meanwhile, leaned into Indiana's Republican-heavy makeup, airing ads attacking Donnelly for voting against Brett Kavanaugh's Supreme Court nomination and for endorsing Hillary Clinton in 2016.
MIKE BRAUN PROFILE
Indiana's next senator is a little-known Republican businessman previously elected to two sleepy terms in the state Legislature, where one of his most notable actions was a vote to increase taxes.
But what multimillionaire auto parts magnate Mike Braun may lack in name recognition, he more than made up for by lending more than $10 million of his own fortune to his campaign.
That enabled him to beat two sitting congressmen, Luke Messer and Todd Rokita, in a bitter GOP primary, and then topple Democratic Sen. Joe Donnelly in Tuesday's general election.
Donnelly was one of the most vulnerable Democrats up for re-election in a state Trump carried two years ago.
Worth somewhere between $37 million and $95 million, Braun came to politics after building a business empire that includes a trucking company and a national auto parts distribution business, Meyer Distributing. It has more than 800 employees and 70 locations across the U.S.
Braun is a graduate of Wabash College and Harvard Business School, where he earned an MBA in 1978. He married his wife, Maureen, in 1976. They have four children.
Before launching his political career as a Republican, Braun voted in Democratic primaries until shortly before he first ran for the statehouse in 2014. He previously served as a member of a local school board.
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The Associated Press contributed to this report.