George W. Bush and Karl Rove claimed electoral mandates when they did not receive them. With the results in from the November 7 elections, Democrats now have a true mandate. They need to claim it aggressively, and without apology. But the only way this will happen is if Democratic leaders in Washington understand why their party won so many races in so many parts of the country.

The election was a repudiation of the Bush presidency, a revolt powered by voters’ opposition to policies they associate with Bush and his allies: open-ended occupation of Iraq, free-trade pacts that favor corporations rather than workers, disdain for the rule of law and ethical standards. The dozens of new Democratic members of Congress–some the conservatives and centrists that pundits so enjoy celebrating but many of them committed progressives–prevailed not because they offered themselves up as kinder and gentler versions of their GOP predecessors but because they understood the public mood. Pennsylvania Senator-elect Bob Casey may be a social conservative, but his campaign highlighted his economic populism and his condemnation of Bush as having “lied to the American people about how we got into Iraq.”

Democrats with a strong antiwar message scored many of the breakthrough wins. They included New Hampshire’s Carol Shea-Porter, who last May declared, “Let us honor our veterans this Memorial Day by saying, ‘Well done, soldier, and welcome home. America needs you here.'” She’ll be joined in the new House by Iowans Bruce Braley and David Loebsack, Minnesotan Keith Ellison and Californian Jerry McNerney, who also won with “Bring the troops home now” messages. Many winners paired opposition to the war with defenses of civil liberties. Montana Senator-elect Jon Tester, chastised by Republicans for criticizing the Patriot Act, took the microphone in a debate and declared, “Let me be clear: I don’t want to weaken the Patriot Act. I want to repeal it.”

Along with antiwar messages, many winners ran as economic populists willing to break with their own party. Ohio’s Senator-elect Sherrod Brown was attacked as being “on the fringe” of the Democratic Party. Brown embraced the criticism, saying, yes, he had broken with the Democratic Congressional leadership to oppose the war, and before that with President Bill Clinton on trade and economic issues. The economic populism that Brown champions–defined largely by smart fair-trade politics–will be amplified by the election to the Senate of Tester, Vermont’s Bernie Sanders and Minnesota’s Amy Klobuchar.

Bush’s name wasn’t on the ballot, so the victims of the anti-Bush wave were all Republicans, including moderates like Senator Lincoln Chafee and Representative Jim Leach, despite their having distanced themselves from Bush. Those who hung on, like Connecticut Congressman Chris Shays, did so by noisily abandoning allegiance to Bush’s Iraq strategies–as did Democrat-turned-independent-turned-Democrat Senator Joe Lieberman, who ended the campaign calling for the removal of Defense Secretary Rumsfeld. It didn’t take long for Bush to meet that demand.

So strong was the Democratic wave that it swept into state and local races. Democrats won a majority of governorships for the first time since the early 1990s, and many of the new governors, such as New York’s Eliot Spitzer and Massachusetts’s Deval Patrick, are activists likely to emerge as national leaders. They’ll be joined by similarly activist Democratic attorneys general like California’s Jerry Brown and Minnesota’s Lori Swanson, and secretaries of state such as Minnesota’s Mark Ritchie and California’s Debra Bowen.

At the federal and state levels, Democratic leaders now have their own “political capital.” How they spend it will decide whether the Democratic wave of 2006 builds or recedes in 2008 and the years beyond. House Speaker Nancy Pelosi’s “first 100 hours” agenda focuses heavily on addressing the ethics crisis in Congress. That’s smart. Many of the seats that fell to Democrats were in districts where Republicans were either forced to resign or had been closely associated with the scandals of GOP lobbyist Jack Abramoff, disgraced House majority leader Tom DeLay or Florida Congressman Mark Foley. Pelosi also plans votes on popular proposals to raise the minimum wage and to implement 9/11 Commission recommendations on national security.

But if Pelosi and Senate Democratic leader Harry Reid want to make their majorities permanent, they must start addressing the more fundamental issues on which so many of their new members ran and won: support for bringing the troops home from Iraq, opposition to the Administration’s free-trade agenda and its tax cuts for the rich, and a determination to clean up our politics by setting higher ethical standards and holding every elected official to account–starting with the President.