U.S. Rep. Steve Rothman says that he's endorsing Barack Obama for a simple reason: he thinks he's the best candidate with the best shot of beating a Republican in the general election.

"I think he is an authentic agent for change, but not only that - he brings to that his extraordinary life experience, his brilliance, his vast knowledge of American and world history and his years as a community organizer as a legislator on both the state and federal level," said Rothman.

But there's another important aspect to the endorsement: it makes Rothman unique.

Out of the five New Jersey Democratic congressmen who have endorsed a presidential candidate, four have gone for Clinton. Three of those four - Frank Pallone, Rob Andrews and Bill Pascrell - are, like Rothman, hopefuls to succeed 83-year-old Senator Frank Lautenberg in the unlikely event that he chooses not to seek another term. Or, for that matter, if Lautenberg wins another term and leaves office part way through it.

Had Rothman endorsed Clinton, he would been another name in a long line of congressmen - at least two of whom, Pallone and Andrews, would be the favorites to be tapped for a Senate seat anyway.

Instead, Rothman has rolled the dice - and if they come up Obama (which seems like less of a stretch than it looked one month ago), he'll be in a good position to either become the next U.S. Senator or at least improve his standing in Congress.

"I think this is another example of Rothman trying to find a way where he could stand out. If he was a supporter of Clinton he would be one of the many. But if lightning strikes, he could be right out there at the front of the line," said Monmouth University pollster Patrick Murray.

There's also the idea that Rothman could be looking to get on the good side of the Congressional Black Caucus, whose former chairman, U.S. Rep. Donald Payne, has a rocky past with Rob Andrews. But while an infusion of black leaders into the state to campaign for Rothman could help a primary campaign along, Clinton polls better with black voters nationwide than Obama does.

Rothman, however, denies any such motivation.

"I picked the best person for the job," he said.

Rothman's gamble has ruffled some Democratic feathers for his aggressiveness. At a Democratic State Convention dinner, Rothman drew scattered boos from the heavily pro-Clinton audience when he said that Obama has "More experience than a certain Senator from New York." And at the New Jersey Presidential Caucus, he drew a similar reaction after saying that a nomination of someone else could result in a loss of congressional seats.

Perhaps getting any boos at all from a room full of Democrats isn't a good sign - that it's worthless to expend political capital drawing hostility from one's own party. But Cook Political Report editor Jennifer Duffy downplayed the significance of endorsements, and doubted that many people would remember or care where Rothman stood during the election of 2008.

"I don't think he has anything to lose," said Duffy.

And if Clinton does wind up becoming the next president, her supporters probably won't hold a grudge, said John F. X. Graham, Clinton's New Jersey finance co-chair. Still, it would be nice if he toned it down a bit.

"I try to ignore anything out there, I try to go past it, but if it becomes a systemic philosophy, I don't think it helps Barack by saying that," said Graham. "He should just talk about Barack's issues and what he can do for the country, not something that could be construed as a personal attack."

Rothman noted that the boos in those two appearances came from a small segment of the audiences -- five percent, by his estimation. And his speech on behalf of Obama at the convention was more evidence of his passion for the candidate, he said.

"At the Convention, there was chatter among some of the Clinton folks about me raising the issue of whether we should pick someone else as our nominee in New Jersey," said Rothman. "They didn't want to hear that, but I raised it. I think it was properly the place to air that discussion amongst the family."

Rothman sees it as his duty to loudly proclaim the merits of who he thinks is his best candidate - even if that means calling into question whether Hillary Clinton is electable. In essence, Rothman said, his speeches in support of Obama reflect the Democratic rank-and-file's desire for the party's elected officials to stop equivocating on issues closest to their ideological foundation.

"I am speaking from my heart about my belief that Sen. Obama will be New Jersey's best candidate for president and America's best candidate for president, and some are objecting because I spoke too forcefully or with too much emotion," said Rothman.

Still, while Rothman denies any trace of political expediency in his decision to endorse Obama, he knows that good things could happen if Obama wins the presidency.

"If Sen. Obama becomes president, will then President Obama remember that I worked hard to make sure that he got elected president? I expect he will," said Rothman.