I think there's generally an assumption that Harry Reid's difficulties in running for reelection are self inflicted but one thing that really should not be underestimated as a factor is how unpopular Barack Obama is in Nevada. His stock has fallen quickly after he won the state big in 2008, and on this poll his approval was just 44% with 52% of Nevadans disapproving of him.
There is close to a 100% correlation between how people feel about Obama and how they're planning to vote in the Senate race. With voters who approve of Obama Reid leads Sharron Angle 94-3. There is basically no one who still likes Obama who isn't planning to vote for Reid this fall. With voters who disapprove of Obama Angle leads Reid 85-7. Reid is not showing much ability to get folks who don't like the President to move beyond that and still support him, although he is enough to give him a small lead.
The most serious threat to Reid's reelection prospects isn't Angle- it's Obama. Reid has to hope the President doesn't get any more unpopular in the state because if he does he might bring the Senator down with him.
Obama's unpopularity in Nevada giving Reid problems is emblematic of a broader trend through the Mountain West. In May we found Obama's approval numbers in Colorado at 45/50, a 14 point drop from his nine point victory spread in 2008. Against that backdrop it's no wonder Democrats are struggling to hold onto the Governor's office and Senate seat they hold there. Obama's also had a particularly acute drop in New Mexico. His approval there when we polled in February was 45/48, a 20 point decline on the spread from his 17 point win there. That's contributing to a Governor's race that's a lot tighter than might have been expected a year ago.
I still think the long term trend in the Mountain West will be toward the Democrats but the short term dramatic decline in Obama's popularity throughout the region is going to be the bigger factor in this year's election.