Democrats who questioned Obama are some of party's most vulnerable in 2010

Politicos watching President Barack Obama's question-and-answer with Senate Democrats might notice a pattern: Many of the lawmakers pressing the president are vulnerable entering the 2010 election.

So far, Sens. Arlen Specter (Pa.), Michael Bennet (Colo.), Blanche Lincoln (Ark.), Kirsten Gillibrand (N.Y.), Evan Bayh (Ind.) Barbara Boxer (Calif.) have taken to the microphones to ask Obama questions and, at the same time, stress their Democratic bona fides.

Nevertheless, each lawmaker is also lagging behind in the political expectations game as the 2010 midterms approach. Specter is trailing Republican challenger Pat Toomey (Pa.) in preliminary polls, despite his six-term incumbency. His primary, too, has proven difficult, if only because he has faced a potent challenge from the left by Rep. Joe Sestak (Pa.)

Meanwhile, Bennet's seat is regarded as a toss-up, and Lincoln has faced near-crippling pressure from her opponents on the healthcare front.

Gillibrand, meanwhile, could face both a tough primary challenge from former Rep. Harold Ford (Tenn.) and, likely later, a tough general election challenge, due to her lagging popularity. Bayh's election, too, might be tough, as he represents a state that typically leans conservative -- a liability during an election year in which voters may rally against the establishment.

And Boxer's Republican opponents number many in 2010 -- and their campaign coffers are equally potent to boot. She may hold the lead in many preliminary polls, but it could still be a tough fight for Boxer.

Lincoln said Democratic leaders had discussed previously who would ask questions at Wednesday's session with Obama.

"In the leadership meeting we talked about it," she said. "I think the majority leader did take a list early on."

- This post was updated at 1:44 p.m.

- Alexander Bolton contributed to this post.

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