HARTFORD — Four years after his unsuccessful bid to unseat Sen. Joe Lieberman ’64 LAW ’67 in the Democratic primary, Ned Lamont SOM ’80 is back.

Tuesday morning Lamont returned to the place where he launched that campaign — the historic Old State House here — and announced he will seek the Democratic nomination for governor of Connecticut.

This comes three months after Lamont formed an exploratory committee for the race. Speaking in the standing-room only General Assembly room this morning, Lamont declared, to great applause: “No more exploring. I’m running for governor.”

In his 17-minute speech, Lamont referred to Science Park at Yale, citing the importance of economic development in the state.

“That’s where Eli Whitney reinvented manufacturing,” Lamont said. “You should be there with other biotechnology companies to reinvent biotechnology.”

Lamont declared that, as governor, he would be the state’s chief economic development officer, and he cited his business experience a number of times in his speech.

In a January Quinnipiac University poll, Lamont led all Democratic candidates bidding to replace retiring Gov. M. Jodi Rell. He was on campus last month to speak to the Yale College Democrats.