WASHINGTON — A usually elusive 60-40 Senate majority is the Democrats' target in Tuesday's election. They are certain to make gains even if they fall short of those magic numbers needed to break Republican chokeholds on their agenda.

Democratic Senate candidates will benefit from any coattail effect a big Obama victory might bring, as well as from the already weak economy and an unpopular war.

Math also favors Democratic Senate candidates this year. With 35 of the Senate's 100 seats on the ballot Tuesday, Democrats have fewer at risk than do Republicans.

After picking up six seats in the 2006 midterm elections to wrest control from Republicans, Democrats have the barest of Senate majorities — 51 seats under their control, including two occupied by independents.

But they are overwhelmingly favored to pick up GOP-held seats in Virginia, New Mexico and Colorado, three states where Republican senators are retiring.

And many Republican incumbents running for re-election are in difficult races. Included in that group is Ted Stevens of Alaska, the longest-serving Republican senator in history, who was convicted earlier this week on seven corruption counts. He's high on the list of top Democratic pickup opportunities, even though Alaska has long been a solid Republican state.

Stevens spurned pleas by John McCain and party leaders to step aside rather than stay in the race against Democratic challenger Mark Begich, the mayor of Anchorage.

Also on the list of endangered Republicans: Sens. Elizabeth Dole of North Carolina, John Sununu of New Hampshire, Norm Coleman of Minnesota, Gordon Smith of Oregon, Saxby Chambliss of Georgia, Roger Wicker of Mississippi and possibly even Senate Minority Leader Mitch McConnell of Kentucky.

No Democratic-held seats appear in jeopardy, and just one Democratic senator, Mary Landrieu of Louisiana, faces a challenge.

Republicans have spent heavily in Louisiana, and the GOP's candidate, state Treasurer John Kennedy, is within reach. But recent polls suggest otherwise.

National Democrats are taking full advantage of the Obama campaign's organizing skills and registration drives, especially in battleground states.

"We've worked hand in glove with the Obama campaign," said Sen. Chuck Schumer, D-N.Y., chairman of the National Democratic Senatorial Campaign Committee.

As to a filibuster-proof majority, "It's hard to get to that 60, and I don't want to oversell it," Schumer said. "But I do think we're going to pick up a large number of seats, and that's going to make Democrats very happy."