Boren remains uncommitted but noted "it's really important to me how my district voted" - for Clinton.
Clinton also met with Reps. Ike Skelton of Missouri, Jason Altmire of Pennsylvania, Ron Klein of Florida and Brad Ellsworth of Indiana, among others.
Clinton's presidential campaign has spent months playing defense while Barack Obama whittled away at her lead in superdelegate endorsements. Her supporters urged undecided superdelegates to hold off on endorsing a candidate - if they weren't ready to back her. Let the primaries play out, they said, and decide which candidate has the best chance to win in November after all the contests are over.
Obama, meanwhile, urged quick endorsements, hoping to build momentum toward the 2,025 delegates needed to win the nomination.
Obama has picked up 83 percent of the superdelegate endorsements since Super Tuesday, narrowing Clinton's superdelegate lead to 259-236, according to the latest tally by The Associated Press. Since Tuesday's primary, Obama has picked up three superdelegates and Clinton has added one.
Superdelegates are the party and elected officials who automatically attend the convention and can support whomever they choose, regardless of what happens in the primaries. They are in high demand now that neither Clinton nor Obama can win the nomination without their support.
There will be nearly 800 superdelegates at the party's national convention this summer. About 60 will be named at state party conventions and meetings throughout the spring.
Obama's campaign sent a memo to superdelegates this week making his case that he has won more delegates and more states than Clinton.
"Our case to superdelegates is the same as it had been, that Barack Obama is the best candidate to bring about the fundamental change that this country needs and the best Democrat to take on John McCain in the fall," said Obama spokesman Bill Burton.
Obama has a 154-delegate lead in pledged delegates won in primaries and caucuses. Clinton will not catch up in pledged delegates in the few remaining contests, but her campaign hopes to narrow the gap.
In the overall delegate race, Obama leads 1,724.5 to 1,593.5. - a 131-delegate margin.
Altmire, who remains undecided, said Clinton asked him to delay endorsing before the Pennsylvania primary. But she was more emboldened at a private meeting in Washington on Wednesday, the day after her victory.
"Both times, that was her message, let's wait and see how this whole thing unfolds. Don't make any rushes to judgment and we'll just see what happens," Altmire said. "And then, of course, she won decisively and now she says that that is the moment that we've been waiting for. You've seen the outcome, and now I'd love to have your endorsement."
About 240 superdelegates remain undecided, and many said they don't plan to endorse until after the primaries conclude June 3.
The AP interviewed more than 100 of the undecided superdelegates in the past three weeks. Many said they hope the nomination is decided before the national convention in August. But they were willing to wait until after the primaries before endorsing a candidate.
"Hillary's message was she knew I was uncommitted and I should not make a decision too quickly, keep my powder dry," Mike Morgan, an undecided superdelegate from Oklahoma, said in an interview before the Pennsylvania vote. "That's what I intended to do. I have a lot of questions about the remaining two candidates."
Robert Rankin, an undecided superdelegate from California, said Obama had the opposite message. "Mr. Obama stated that for the good of the party he believed that we should come together and get it done in a way we could start working on the general election," Rankin said. "There is a valid point to that. I don't necessarily disagree with it. But I'm not ready to do it until I hear from the other states."
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Associated Press writers Ron Jenkins in Oklahoma City, Okla.,
and Kimberly Hefling in Washington contributed to this report.
