Along those same lines, many of the most vulnerable Democrats are longtime incumbents, while most of the most vulnerable Republicans are freshmen. Those Democrats, in addition to having the fortitude to survive a disastrous 2010, have built their political brands over multiple terms in Congress – an opportunity that has simply not been afforded to GOP freshmen.

“Republicans are the ones who now represent swing districts, so they’re not just getting rave reviews from their base; they’re also getting mediocre reviews from independents,” said GOP pollster Jon McHenry. “Democrats have been largely beaten back to their core constituencies, so their numbers come primarily from base supporters.”…

Democratic pollster Jef Pollock, though, says it has a lot to do with the tea party as well.

“It doesn’t help that in some of these districts where tea party candidates won, the tea party is perceived poorly,” Pollock said. “The voters have sipped their brand of tea and it hasn’t tasted particularly good.”