WASHINGTON (MCT) — The political tide of new voters and economic anxiety that swept Barack Obama into the White House has armored him with a more formidable Democratic majority on Capitol Hill to push his agenda.

With returns still being counted, Obama's coattails helped to topple at least five Republican Senate seats. Democrats were also making gains in the House, hoping to add 20 seats or more.

In Senate races, Democrats unseated Republican incumbents Elizabeth Dole in North Carolina and John Sununu in New Hampshire. They also won three open contests where veteran Republican lawmakers were retiring.

In Virginia, Democrat Mark Warner defeated Republican Jim Gilmore in a battle between two former governors. In New Mexico, Democratic Rep. Tom Udall defeated Republican Rep. Steve Pearce.

And in Colorado, Democratic Mark Udall — Tom Udall's cousin — beat Republican Bob Schaffer.

There will be no shortage of reasons for the GOP implosion. President Bush's plummeting popularity was a big one. He was virtually absent from the campaign but an albatross for Republicans nonetheless.

From the war in Iraq, which a majority of the public opposes, to the economic crisis, which has been the called worst since the Great Depression, Republicans struggled with how to navigate a political terrain for which they seemed to have no compass.

Obama and the Democrats were more surefooted.

"The Republican playbook that worked for them for a generation, that's become an anachronism," said Simon Rosenberg, president of the New Democrat Network. "There's a new voting population, new coalitions, new issues, new media. The Republicans have been fighting the future. That is one of the reasons why they are in trouble. They've gotten on the wrong side of history."

Their victories give Democrats a 56-seat majority. That includes two independents, Sens. Bernard Sanders of Vermont and Joseph Lieberman of Connecticut,.

But Lieberman's future is a question mark. The party's 2000 vice-presidential candidate angered Democrats because he supported Republican John McCain and criticized Obama.

More Republican incumbents could still fall. But the goal of a 60-vote, filibuster-proof majority looks to be nearly impossible. That's how many votes Democrats would need to sidestep Republican efforts to block their legislative efforts.

To get there, Democrats would have to defeat all remaining endangered Republicans: Sens. Ted Stevens in Alaska, convicted of corruption last month; Gordon Smith in Oregon, a moderate who linked himself to Obama; and Norm Coleman in Minnesota. In Georgia, incumbent Saxby Chambliss was ahead.