NEW ORLEANS — Senator Edwards launched his second campaign for the White House from this flood-ravaged city yesterday with a call for America to reduce its troop presence in Iraq and a plea for citizen action to combat poverty, global warming, and America’s addiction to foreign oil.

Mr. Edwards was sharply critical of the administration for its conduct of the war in Iraq, even as he again recanted his own vote authorizing President Bush to take the country to war, which he called a mistake.

“We need to make it clear that we intend to leave Iraq and turn over the responsibility of Iraq to the Iraqi people,” Mr. Edwards told reporters.

Mr. Edwards said he favors withdrawing 40,000 to 50,000 troops from Iraq as a signal to Iraqis that America intends to turn over responsibility for the conflict to the government there. Wading into the current debate in Washington about Iraq, he forcefully rejected proposals to send more troops to help quell the bloody sectarian violence.

“I want to be absolutely clear about this,” he said. “It is a mistake for America to escalate its role in Iraq. It is a mistake to surge troops into Iraq. It sends exactly the wrong signal to the Iraqis and the rest of the world about what our intentions are there.”

Mr. Edwards also said he favored rolling back some of the tax cuts given to the wealthiest Americans by the Bush administration and proposed a windfall profits tax on the oil industry, saying additional money will be needed to pay for vital domestic needs.

“I think it’s also really important that we be honest with people,” he said. “We’ve gotten in a deep hole, in terms of our deficit. We have investments that need to be made.”

From the choice of setting to the candidate’s message, Mr. Edwards used the opening day of his 2008 campaign to signal that he intends to run a populist, insurgent campaign designed to show that he is not a candidate of Washington.