Beyond the Dome

There’s a subtle, but potentially important, difference between the congressional superdelegates Barack Obama has won since Tuesday’s primaries and the superdelegates Hillary Rodham Clinton has won.

This morning, Rep. Donald M. Payne of New Jersey switched his support from Clinton to Obama, and Rep. Peter A. DeFazio endorsed Obama as well, just in time for the Oregon primary May 20. This afternoon, Rep. Mazie K. Hirono of Hawaii endorsed him too.

Yesterday, Obama picked up Rep. Brad Miller of North Carolina and Rick Larsen of Washington state.

Clinton, meanwhile, picked up the support Rep. Christopher Carney of Pennsylvania this morning. Reps. Heath Shuler of North Carolina and Brad Ellsworth of Indiana insist they haven’t officially endorsed her – even though her campaign cited both of them as new endorsements. But both are promising to vote for the winner of their districts if the nomination fight goes all the way to the convention, who just happens to be Clinton.

So here’s the difference: Most of Obama’s new congressional supporters have been around a while, and have pretty safe seats. Even Hirono, the one freshman out of the bunch, won her heavily Democratic district in 2006 with 61 percent of the vote.

Clinton, however, is picking up the first-term Democrats who won their seats away from Republican incumbents. In other words, they’re the ones who made it possible for the Democrats to win the House in 2006.

One of Clinton’s major arguments against Obama, of course, is that she’s winning the swing states and key demographic groups that a Democrat would need to win the White House. But there’s another way to look at the issue: the Democrats only have control of the House because they were able to win 30 seats away from the Republicans. If those first-term Democrats decide she’s the stronger candidate to help them keep their seats – or even if they just feel obligated to vote for her because their constituents did – that’s a trend that should catch the attention of the Obama campaign.

It’s not clear that these Democrats are lining up with Clinton with a lot of enthusiasm. Even Carney, who released a formal statement Friday morning, simply said that “Pennsylvania’s 10th District overwhelmingly chose Senator Clinton in the Pennsylvania primary and I will respect their decision.”

But if Obama wants to assure his Democratic colleagues that he can not only win in November, but help them win too, he may need to devote more attention to the ones that are on the shakiest ground.