As a somewhat stark reminder of just how difficult a year this is going to be for Democrats, look at how many Democratic incumbents are polling under 50% in the RCP Average at the moment:

Blanche Lincoln (AR) is at 35.0% against John Boozman.
Harry Reid (NV) is at 41.0% against Sharron Angle.
Michael Bennet (CO) is at 42.7% when matched up against Jane Norton and 43.0% against Ken Buck.
Patty Murray (WA) is at 46.3% against unknowns Clint Didier and Paul Akers and she's at 45.7% against Dino Rossi.
Barbara Boxer (CA) is at 46.6% against Carly Fiorina.
Kirsten Gillibrand (NY) is at 48.0%, 48.3%, and 48.7%, respectively, against three no-name Republicans.
Russ Feingold (WI) is at 49.7% against Dave Westlake. Feingold was at an even lower 48.5% in the RCP Average against Terrence Wall before he dropped his bid at the beginning of the month, and a new Rasmussen poll shows Feingold at a mere 46% and in a statistical tie with Republican newcomer Ron Johnson.

Outside of Bennet and Gillibrand, these are exceedingly well-established members of the Democratic Senate caucus. As you can see, in Arkansas (which votes Republican at the Presidential level but heavily Democratic at the state level) and in the swing states of Nevada and Colorado, Democratic incumbents aren't even within spitting distance of 50%, while those in deep blue states (NY, CA, WA and to a lesser degree WI) are also falling short of majority support. (Note: Two recent polls show Ron Wyden at 51%, which is also pretty soft, but given the quality of Wyden's opposition his seat looks safe at the moment.)

By contrast, Republicans have just two incumbents hovering below the 50% mark in the RCP Averages right now:

David Vitter (LA) is at 49.5% against Charlie Melancon.
Richard Burr (NC) is at 50.0% against Elaine Marshall, who won the Democratic runoff tonight in North Carolina.

Burr and Vitter's numbers are soft for incumbents, especially in a good year for Republicans running in red states, but they also currently hold comfortable leads over top tier Democratic challengers: Vitter is up by 15.7% over Melancon, and Burr is up 15.3% over Marshall.

Obviously, not all of the Democrats under 50% are going to lose, and it remains a real long shot for Republicans to pick up the eleven seats they would need to retake control of the Senate. But the weakness displayed by Democratic incumbents just four months before voters go to the polls has to have the party bosses wondering and worrying just how bad the bloodbath might be on Election Day.

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