Dan Koh of Andover won the Democratic primary for Massachusetts' 6th Congressional District on Tuesday, Sept. 1, beating five rivals in a race to replace U.S. Rep. Seth Moulton.

The Associated Press called the race for Koh at 10:27 p.m. With 63 percent of the vote counted, Koh led state Rep. Tram T. Nguyen of Andover 42.3 percent to 29.5 percent, the Marblehead Independent reported. John Beccia finished third at 12.3 percent, followed by Jamie Belsito at 8.6 percent and Mariah Lancaster at 3.7 percent.

The race drew more than $10.5 million in spending from candidates and outside groups, according to Andover MA News. Koh raised more than $4.7 million. Outside groups spent more than $1.7 million supporting him. Beccia loaned his campaign nearly $4 million. Outside groups spent nearly $680,000 backing Nguyen.

Koh, a former chief of staff to Boston Mayor Marty Walsh and a Biden White House aide, lost a 2018 congressional primary to U.S. Rep. Lori Trahan by 145 votes. In his victory speech Tuesday night, he traced his path to his family's immigrant roots.

"I know that tonight, I stand on their shoulders," Koh said in his Sept. 1 victory speech.

He will face Republican Micah Quinney Jones in the Tuesday, Nov. 3 general election. The Cook Political Report rates the 6th District 11 points more Democratic than the nation.

Nguyen, who came to the United States from Vietnam as a 5-year-old refugee and became the first Vietnamese American woman elected to the Massachusetts Legislature in 2018, ran with far less money.

Markey defeats Moulton in Senate primary

Sen. Ed Markey defeated Rep. Seth Moulton in the Democratic Senate primary by roughly 76 percent to 24 percent, according to the New York Post. Moulton's decision to leave the 6th District seat opened the race Koh won.

Moulton and his allies outspent Markey's side $7.1 million to $3.9 million on ads, NBC News reported. The spending gap did not matter.

Markey, 80, will face Republican John Deaton in the general election. CNN reported that Markey said he will not seek a fourth term if reelected.

Down-ballot races

In the Republican gubernatorial primary, Michael Minogue defeated Brian Shortsleeve and will face Gov. Maura Healey in the general election. Healey ran unopposed in the Democratic primary.

Connor A. Murray of Andover ran unopposed in the Democratic primary for the 18th Essex state House seat Nguyen vacated to run for Congress. The district covers parts of Andover, Boxford, North Andover and Tewksbury. Murray will likely face Republican Christopher Shepley, who ran a write-in campaign, in November, WHAV reported.

North Andover state Rep. Adrianne Pusateri Ramos and state Sen. Barry R. Finegold faced no primary challengers. Finegold will face Republican Theodore T. Semesnyei in November.