Barack Obama should not pick Hillary Clinton as his vice-presidential nominee, former president Jimmy Carter has told the Guardian.
"I think it would be the worst mistake that could be made," said Carter. "That would just accumulate the negative aspects of both candidates."
Carter, who formally endorsed the Illinois senator last night, cited opinion polls showing 50% of US voters with a negative view of Clinton.
In terms that might discomfort the Obama camp, he said: "If you take that 50% who just don't want to vote for Clinton and add it to whatever element there might be who don't think Obama is white enough or old enough or experienced enough or because he's got a middle name that sounds Arab, you could have the worst of both worlds."
Carter, who insisted that he would have been equally against an Obama-Clinton pairing if the former first lady had won the nomination, made the remarks in an interview with the Guardian's Weekend magazine, to be published on Saturday. The interview was conducted before the final round of voting last night confirmed Obama as the party's presumptive nominee.
The intervention of the former president - regarded as the senior elder of the Democratic party by some, and as a walking reminder of electoral failure by others - comes just as speculation of a joint Obama-Clinton ticket is building in the US. Lanny Davis, a close Clinton adviser and friend, has launched a petition drive and website - and written directly to Obama - urging him to appoint his defeated rival.