After Christine O’Donnell won the Republican nomination for the Senate race in Delaware, Democrats appeared to heave a sigh of relief.  The long-shot path to losing the Senate appeared to require the GOP to take Joe Biden’s old seat, and with Mike Castle sidelined, their control of one chamber of Congress looked assured.  Not so fast, warns political analyst and prognosticator Stuart Rothenberg at CQ Politics:

Delaware’s Republican primary may well have lulled Democrats into a sense of complacency about their ability to hold the Senate after November’s elections. They would be wise to wake up if they want to avoid a nasty surprise on election night. …

With a month to go until Nov. 2, Republicans have a clear advantage in five seats held by Democrats, with another five seats still in play.

Unless things change, Republicans will likely hold all 18 of their seats up this cycle. No GOP incumbent is in any trouble — even Sens. Richard M. Burr(N.C.) and David Vitter (La.), who seemed at some risk early on, look headed for comfortable victories — and Republican open seats appear to be at limited risk.

Rothenberg figures the GOP to take seats away from Democrats in North Dakota, Arkansas, Indiana, Pennsylvania, and Wisconsin.  The GOP has an edge in Illinois as well, giving them six pickups.  If Ken Buck stays ahead in Colorado and Sharron Angle can take advantage of Harry Reid’s unpopularity in Nevada, that will be eight seats.

Republicans would just need to split four other races in Washington, Connecticut, California, and West Virginia — and this is where it starts to look interesting.  John Raese is moving ahead of Joe Manchin in WV, where conservative voters don’t want to send another Democrat to the Senate to replace Robert Byrd.  Linda McMahon is closing in on Richard Blumenthal in Connecticut, making it a virtual dead heat.  And the news out of Washington suddenly got worse for Democrats, according to the latest Rasmussen survey:

Incumbent Democratic Senator Patty Murray and Republican challenger Dino Rossi are back to a virtual tie in Washington’s race for U.S. Senate.

The latest Rasmussen Reports statewide telephone survey of Likely Voters shows Rossi picking up 48% support, while Murray earns 47% of the vote when leaners are included. Two percent (2%) prefer some other candidate, and three percent (3%) are undecided. …

Two weeks ago, Murray moved to a modest 51% to 46% lead over Rossi when leaners were part of the totals. In 10 previous surveys from January through August, the candidates have been within two points of each other seven times. Murray’s support has ranged from 45% to 50%, while Rossi has picked up 46% to 49% of the vote.

Rossi wins the independent vote by a wide margin, 60/32 with leaners.  He wins thirtysomethings by a wider margin than he loses younger voters, and ties Murray among seniors.  Rossi also wins every income demographic except <$20K voters, with majorities in all but the $20-40K demo.  Rossi also has a slight edge on favorability, 50/46 to Murray’s 47/48, which may influence how late-breaking voters decide.  Also helping Rossi will be the wide majority that believes that federal policies have the country on the wrong course, 54%, as opposed to only 29% that endorse the policies represented by Murray.

Republicans have a shot at all four races mentioned by Rothenberg as the long shots.  It’s possible to pick up not eight or nine, but eleven or even twelve.  It’s still a long shot to do so, but a big wave on Election Day may carry Connecticut and California, while Rossi seems to be picking a good time to show momentum, as voters will start casting ballots by mail in the next couple of weeks.  It certainly will make for an exciting Election Night.