Democrats endorsed Sen. Joe Lieberman’s bid for a fourth term but an anti-war challenger collected enough delegates to force the senator into his first primary fight as an incumbent.

Ned Lamont, a wealthy Greenwich businessman who has sharply criticized the moderate senator for supporting the war in Iraq, will face Lieberman in the Aug. 8 primary.

Lieberman won 1,004 of the 1,509 votes cast at the state convention. But Lamont captured 505 votes, or 33 percent of the delegates, well more than the 15 percent he needed to force the primary.

Sean Smith, Lieberman’s campaign manager, downplayed Lamont’s delegate support.

“There are 600,000 Democrats who are going to be heard from before this is over,” he said.

Lieberman reminded convention delegates Friday that he stands for more than his support for the war. He said he had called hundreds of delegates in recent weeks, talking about the environment, his support of the submarine base in Groton, education and other issues.

“I’m a proud Democrat, and I’m going to carry the battle forward,” said Lieberman, who has not faced a primary challenge since being elected to the Senate in 1988.

Lamont said he believes the level of support he received at the convention will send a message to Washington that people are fed up with the war.

“They are saying this war was a mistake and bring the troops home,” he said.

Lamont is from an old-money Connecticut family with strong Wall Street ties. He founded his own telecommunications firm, Lamont Digital Systems, in 1984.

Lieberman became a national political figure as his party’s vice presidential nominee in 2000. He unsuccessfully sought the presidential nomination four years later.