Delaware Sen. Tom Carper's current margin of victory is unusually small one for a sitting senator who has been a fixture of his state's politics for longer than his challenger has been alive. | Zach Gibson/AFP/Getty Images Carper fends off Delaware primary challenge The Democratic senator survived a primary challenge in Delaware, defeating Air Force veteran Kerri Harris.

WILMINGTON, Del. — Sen. Tom Carper won his Democratic primary in Delaware Thursday, overcoming a liberal challenger looking to build on a national wave of left-wing energy and deny Carper’s bid for a fourth term.

Carper defeated Kerri Evelyn Harris, a 38-year-old Air Force veteran running on a progressive platform that contrasted with Carper’s moderate, pro-business record. He won 65 percent to Harris' 35 percent, a comfortable margin — but an unusually small one for a sitting senator who has been a fixture of his state's politics for longer than his challenger has been alive.


“This is a good win, a solid win,” Carper told supporters at an election night watch party here. “I want to congratulate Kerri on a good race — a very good race.”

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Harris hit Carper for his coziness with the pharmaceutical industry and other big businesses in the corporate-friendly state. She campaigned in the final week before the primary with Alexandria Ocasio-Cortez — the young liberal woman who unseated Rep. Joe Crowley (D-N.Y.) in a primary back in June — and Harris and her allies worked to link her candidacy to other successful progressive candidates storming through Democratic primaries this year, like Ayanna Pressley in Massachusetts and Andrew Gillum in Florida.

After the loss, Harris endorsed Carper and cast her campaign as a partial victory, in that it forced the senator to engage or change on certain issues.

"Ongoing, vocal, public support for our progressive values will eventually help shift our legislators towards solving our common concerns," Harris said to supporters Tuesday night. "In the course of this election, Senator Carper has already shown that he’s eager to listen to Delawareans, and that is why he has embraced their call for a $15 minimum wage and the rescheduling of marijuana."

Carper also voted for the Keystone Pipeline and approved Brett Kavanaugh’s lower-court nomination during the Bush administration — two votes that Harris and her allies raised repeatedly during the primary. But Carper, who says he now regrets voting for Kavanaugh, said his experience and seniority made him a more effective voice to fight President Donald Trump in the Senate.

He was first elected to the Senate in 2000; before that, he served as state treasurer, five terms as the state’s lone congressman and two terms as governor.

In an interview with POLITICO at the minor-league ballpark that hosted his election night event, Carper touted his experience in creating jobs, both as a legislator and as governor — experience he said Harris doesn't have.

"I know how to do it still. With all due respect, I’m not really sure that my opponent is that well-steeped in it," he said. "She shouldn’t be. I’ve been doing this forever. But I think we agree on the broad principles. There’s some disagreement on how to get there."

Carper also didn't sweat the size of his win — much narrower than his 76-point victory six years ago.

"Anytime you win, it’s a win, and you’re grateful for that," he said. "It’s a bigger margin than I think a lot of people expected. I think a lot of people across the country thought I could very well lose the race."

Ultimately, Harris was unable to build on the liberal energy that others like Ocasio-Cortez, Pressley and Gillum harnessed in their contests. She raised only $121,000 for her bid through mid-August. Carper raised $2.4 million — 60 percent of which came from political-action committees. (Though Delaware is a small state, most voters live in the pricey Philadelphia media market, making TV advertising expensive.)

Carper, 71, told POLITICO last week he wasn’t taking the primary for granted. But it was the toughest race he’d faced in nearly two decades, when he won the Senate seat by ousting the GOP incumbent, Bill Roth, in the 2000 election.

Carper will be a heavy favorite in the general election against Robert Arlett, a Sussex County councilman who won the GOP primary on Thursday.

The primary was held on a Thursday rather than the traditional second Tuesday in September to avoid coinciding next week with Rosh Hashana, the Jewish New Year.

In his speech, Carper signaled he would operate much the same way he has in his first three terms if he's reelected in the fall.

"We need people who have experience,” he said. “People who have strong principles, strong values. And also people who can work across the aisle when that’s important.”

But, in his next sentence, Carper signaled he isn't about to align with the Republican president: “We need somebody to stand up against this guy, Trump.”