BEAVERTON, Ore., May 10 (UPI) -- More superdelegates say they are are backing Sen. Barack Obama in the wake of his strong showing in this week's U.S. Democratic presidential primaries.

As Obama campaigned in Oregon Friday, he picked up nine more superdelegate endorsements, including one former supporter of Democratic rival Sen. Hillary Clinton. By various counts, it either gave Obama his first lead in the crucial superdelegate count or enabled to pull even with her.

Rep. Donald Payne (D-N.J.), an early supporter of Clinton, declared he had switched his preference to Obama.

"After careful consideration, I have reached the conclusion that Barack Obama can best bring about the change that our country so desperately wants and needs," Payne told the Newark Star-Ledger Friday. "I've really been mulling it over for quite a while."

Despite the move of superdelegates to his camp, Obama insisted his struggle with Clinton for the nomination isn't over and speculation over his potential vice presidential running mates was premature.

"We do not have this nomination locked up," he told reporters in Beaverton, Ore. "Until I am the nominee, I don't want to speculate on running mates."