Democrats may hold up to 57 U.S. Senate seats after the 2008 election - almost enough to block a Republican filibuster and likely enough to assure passage of most of the Democratic program.

Last week was a bad one for the GOP. Longtime Sens. John Warner (R-Va.) and Chuck Hagel (R-Neb.) announced that they wouldn't seek re-election in '08, joining Sen. Wayne Allard (R-Colo.) in voluntary retirement. Add to that Sen. Larry Craig's (R-Idaho) involuntary retirement.

Republicans may well lose the Warner seat - Sen. George Allen lost in '06 to Democrat Jim Webb in Virginia. The most likely Democratic candidate, ex-Gov. Mark Warner, probably can't be beaten.

The Colorado seat is likely to go Democratic, too. The strongest GOP candidates aren't running; ex-Rep. Bob Schaffer will likely face off against the Democrats' Rep. Mark Udall. With major Hispanic immigration, Colorado has become more and more blue: Witness the election of Democrat Ken Salazar to the Senate in '04.

The GOP should hold Nebraska and Idaho. Only popular ex-Sen. Bob Kerrey could win Nebraska for Democrats, and he'd have to leave his job at the New School University. Idaho's in play only if Craig recants his resignation and stays in office until his term is up in '08.

But four other GOP incumbents are in big danger next year. Oregon's Sen. Gordon Smith boasts a job approval below 50 percent. He's already the only Republican senator on the West Coast.

Nearly as endangered a species is the New England Republican. Sens. John Sununu of New Hampshire and Susan Collins of Maine face '08 jeopardy, too. Sununu narrowly defeated ex-Gov. Jeanne Shaheen in '02; she might well win in '08. In the American Research Group poll, she beats Sununu by 57 percent to 29 percent; in the University of New Hampshire poll, it's 54-38.

Collins will face a tough challenge from Democratic Rep. Tom Allen. Her support of the Iraq War will likely cost her in Maine, one of the most liberal states.

Meanwhile, in Minnesota, Democrat-turned-Republican Sen. Norm Coleman faces a tough fight for his second term. He has backed the war and opposed abortion, unpopular positions in liberal Minnesota. His approval rating has dropped below 50 percent, with only 43 percent having a favorable opinion of him. And it looks like he won't be lucky enough to draw comedian Al Franken as his opponent after all: Attorney Mike Ciresi will likely beat Franken in the Democratic primary.

Finally, Sen. Ted Stevens (R-Alaska) may be under federal indictment by next November. The FBI recently raided his home in a bribery scandal. His seat would likely stay Republican, but might slip away.

The GOP might pick up some Democratic seats, too - as long as the presidential race is not a Democratic landslide. Sens. Mark Pryor (D-Ark), Mary Landrieu (D-La.) and Tim Johnson (D-S.D.) could all be in danger. And Joe Biden (D-Del.) may retire. But, in a Democratic year, all these seats may be safe.

If the Republicans lose Virginia, Nebraska, Colorado, New Hampshire, Maine, Oregon and Minnesota - and pick up no new seats - the Democrats will have 57 votes in the Senate (counting Independent Sen. Joe Lieberman, who votes with them). It's enough to let a new Democratic president have her way legislatively without too much trouble.