The Democratic establishment scored a major victory over the party’s progressive wing on Tuesday when Shontel Brown defeated Nina Turner in a primary election in Ohio.

Conceding defeat, Turner told supporters: “Tonight my friends, we have looked across the promised land, but for this campaign, on this night, we will not cross the river.”

The contest was seen as a bellwether for the party six months into Joe Biden’s presidency and 15 months ahead of the midterm elections for Congress.

Brown was endorsed by Hillary Clinton, the former secretary of state and presidential nominee, and James Clyburn, the highest ranking African American in the House of Representatives.

Turner had the backing of senator Bernie Sanders, a democratic socialist who twice ran for president, and congresswoman Alexandria Ocasio-Cortez, a leading member of “the squad” of progressives.

The campaign in Ohio’s 11th congressional district, triggered by the resignation of Marcia Fudge to become housing secretary, had turned increasingly nasty in recent weeks with money pouring in from outside groups and both candidates under attack from negative TV ads.

But 46-year-old Brown’s victory in the safe Democratic district will be interpreted by moderates as proof that the party should hold the centre ground and not shift to the left.

It follows Biden’s win over Sanders in the presidential primary, the moderate Eric Adams’ triumph over progressives in the New York mayoral race and centrist Terry McAuliffe’s victory in the Virginia gubernatorial primary.

“Once again, the pundits and the Twitterverse got it wrong, and Democratic voters picked the moderate, Shontel Brown, over the candidate ordained by the far left,” said Matt Bennett, executive vice-president of the centre-left thinktank Third Way.

“Ever since Secretary Fudge resigned her seat, the conventional wisdom has held that the Democratic nomination in this special election would go to the loudest and most radical of the candidates. But as we’ve seen in so many recent primaries, Democratic voters in OH-11 had other ideas. They have chosen Shontel Brown, a committed Biden Democrat, to represent them in Washington.”

Brown had emphasised her support for Biden’s administration and drew a contrast with Turner, who was co-chair of Sanders’ 2020 presidential run. In an interview with the Guardian at her campaign headquarters in Cleveland last week, Brown said: “The other candidate already made a commitment to be a part of the squad. I’m running to be a member of Congress.

“That’s what people care about. Who’s going to deliver for them? I’m not looking to make headlines and not looking to get a lot of attention, I want to be effective. I want to help people. People are struggling here and so being able to deliver relief and recovery and resources will be my highest priority.

“Being an effective member of Congress is more important to me than joining any type of group that has been getting a lot of attention.”

The campaign reached a climax on Saturday when Clyburn and Sanders came to Cleveland to champion Brown and Turner respectively. Sanders’ influence was questionable: he lost the district convincingly to Clinton in 2016 and Biden in 2020.

The candidates raised more than $6m, making it the most expensive special House election this year, according to OpenSecrets.org, the website for the Center for Responsive Politics.