Democratic Rep. John Larson — who has represented central Connecticut since the late 1990s — lost his party’s primary Tuesday to former Hartford Mayor Luke Bronin, CBS News has projected, after a campaign dominated by debates about generational change.

With just over half of the vote counted at around 10:15 p.m. ET, Bronin led Larson by just under 20 percentage points, or nearly 7,000 votes. West Hartford state Rep. Jillian Gilchrest and Hartford Board of Education member Ruth Fortune trailed the two front-runners.

The candidates for the reliably blue Hartford-area House seat agreed on many key policy issues. Instead, the primary turned on whether Democrats should send a longtime lawmaker back to Congress or opt for a newer — and younger — candidate. Larson, 78, was seeking a 15th term in Congress, while Bronin was 31 years younger than him.

Bronin focused heavily on that theme. His campaign website promised “new energy, new ideas, and new perspectives,” and he cast Larson as a “status quo” candidate, telling voters: “The stakes are too high to keep doing the same thing.”

The Connecticut Democratic Party endorsed Bronin over Larson at its convention in May, an upset that prompted Bronin to call on his rival to “pass the torch.” Bronin was also endorsed earlier this year by Biden-era Transportation Secretary Pete Buttigieg, who ran for president in 2020 and is widely viewed as a possible 2028 contender.

Larson, meanwhile, presented his long tenure in Congress as an asset, arguing he has delivered for constituents and — as one of the longest-serving House Democrats — would have more sway. 

House Minority Leader Hakeem Jeffries, a New York Democrat, campaigned for Larson.  

“We are going to come in as a full committee chairman, not as some freshman in Congress with some assignment,” Larson told Hartford CBS affiliate WFSB-TV.

Bronin raised just over $3 million during the primary, ahead of Larson’s $2.7 million.

Bronin will now face Republican nominee Amy Chai, who ran for her party’s nomination unopposed.