The Bush administration was forced to step in to mend problems with the new Medicare prescription drug programme yesterday, promising to reimburse states for money they have spent to provide medicine to people whose benefits were delayed.

The decision to intervene is an embarrassing setback for President George W. Bush, who has listed the programme among the primary accomplishments of his first term. But it reflects growing pressure from Republican and Democratic governors, as well as members of Congress, following reports that trouble enrolling in the programme has left hundreds of thousands of people without coverage since it took effect on January 1.