Sen. Claire McCaskill remains the “most vulnerable Democrat” running for re-election, according to National Journal’s Hotline, a daily digest of political news.

Meanwhile, her campaign announced that she had raised $1.4 million during the last quarter of 2011 and had nearty $5 million in cash on hand.

In publicizing the number via Twitter, Campaign Manager Adrienne Marsh said it was McCaskill’s “best fundraising quarter yet.”

The latest Hotline monthly look at the battle for the Senate ranks Missouri as the third most likely seat to change party control. However, it noted that the Republican field was McCaskill’s “best friend” because each of her potential opponents has some drawbacks.

It said that Republicans believe former state Treasurer Sarah Steelman might be “unelectable” and that Rep. Todd Akin was a “lackluster fundraiser.” St. Louis businessman John Brunner, is an untested candidate, but Hotline said he is improving.

The GOP field has begun debates, although Brunner has so far declined to attend any. But overall, Republicans are encouraged that the public mood, high unemployment and McCaskill’s longstanding ties to President Obama will be a boon to their cause.

Democrats, meanwhile, hope that despite the president’s unpopularity in Missouri, the slow, but seemingly gradual improvements in the economy will make McCaskill’s road a little easier. But few believe her re-election will be easy.