Tony Blair's credibility as Prime Minister is on the line in his battle to require British university graduates to pay about $5,100 per year in fees after entering the workforce. The measure has sparked a rebellion in his Labour Party. More than 140 Labour MPs have signed a motion opposing the plan, forcing Blair to delay a vote until January. If he fails to win enough support to pass his pet scheme for providing new funding for British universities, he may face pressure to resign. Blair's likely successor would be Chancellor of the Exchequer Gordon Brown, who doesn't hide his ambition for the job. EDITED BY Edited by Rose Brady