A telecommunications executive announced plans Monday to challenge Sen. Joseph I. Lieberman for the Democratic nomination, hoping to win over voters turned off by Lieberman's support for the war in Iraq.

Greenwich businessman Ned Lamont represents the first opposition Lieberman has faced within his party during his 18 years in office.

Lamont hopes to win the support of Democrats uncomfortable with Lieberman's stand on Iraq and his perceived closeness to President Bush's administration.

"Our troops are making their country proud with their service," Lamont said on his campaign Web site. "But this war is not making us any safer. It's time for U.S. troops to move to the background and let the Iraqi people step forward and take responsibility for their own destiny."

Lamont, a 52-year-old graduate of Harvard and the Yale School of Management, founded his own telecommunications company, Lamont Digital Systems, in 1984. He said he is prepared to spend some of his own money on the campaign.

Although Lieberman's popularity in Connecticut has suffered somewhat, he remains a very strong candidate, said Quinnipiac University poll director Douglas Schwartz.

"Yes, we've seen his numbers drop among Democrats, but he still enjoys a good approval rating among Democrats," Schwartz said. "And his support for the war has helped boost him with Republicans, which has kept his overall approval rating high."

A recent Quinnipiac poll found that 68 percent of registered Democrats said they would vote for Lieberman, while 13 percent said they would back Lamont.

"I can't see how he can upset Lieberman," Schwartz said. "Even if he wins all of the people who are unhappy with Lieberman's support of the war, that's still not enough to win the primary."