Democratic Party Chairman Howard Dean said Tuesday that Sen. Barack Obama (D-Ill.) will unveil “a different message for a different audience” in the general election campaign, as opposed to the one he used to capture the Democratic presidential nomination.

But he told a breakfast fundraiser for a fellow Vermont Democrat, Sen. Patrick Leahy, that Obama still has to rely on campaign workers knocking on doors and taking that message to prospective voters, just as they did during the primaries.

“The same mechanism he used in the primaries will win in the general election,” Dean said. “Obviously, it’s a different audience. But he’s running an incredibly sophisticated campaign.”

Earlier, Dean told some 150 lobbyists that Michelle Obama “hit a home run” with her speech to the convention Monday night.

But he added, “This election is not going to be about great speeches. It’s going to be about having people knocking on doors, not once but two, three and four times. This is how Barack Obama won the primaries. He’s going to take that model and use it for the entire country.”

He warned, as Dingell and others have, that Republicans will unleash a barrage of “dirty” ads against Obama and his running mate, Sen. Joseph Biden of Delaware, after they are nominated. To counter that, he said, Democrats must convince voters to cast their ballots early and “lock up 30 percent of the votes.”

Dean called Obama “a candidate who has such great appeal that he can win in states that we haven’t won in a long time,” including states like Kentucky and Tennessee. He also said Democratic candidates for the House and Senate “are competitive in states where we never have been competitive before.”

Dean praised Leahy, chairman of the Judiciary Committee, as “the conscience of the Senate,” and said, “Without Pat Leahy, Alberto Gonzales would still be attorney general of the United States.”

Leahy was joined by Sens. Sheldon Whitehouse (D-R.I.) and Bernie Sanders (I-Vt.), as well as Senate candidate Al Franken of Minnesota and Vermont gubernatorial candidate Gay Symington. He said the “stakes are too high” this fall for Democrats to lose the White House, declaring that the next president will name “three new Supreme Court justices in the next four years.”

Leahy, who is a longtime fan of the Grateful Dead band, introduced one of its members, Mickey Hart, and held up a campaign button that said “Deadheads for Obama.”