WASHINGTON - As the Democratic presidential nomination race winds down, talk grows about a possible Barack Obama-Hillary Clinton ticket, according to media reports. Time magazine reported that former U.S. President Bill Clinton is considering the role change for his wife if she cannot win the Democratic Party's nomination for president. But, Sen. Hillary Clinton, Democrat from New York, has insisted all along that she is interested only in the presidency and both camps have shrugged off any idea of a joint venture. The chief strategist for the Senator Barack Obama, Democrat of Illonois, campaign, David Axelrod, told reporters no overtures had been made by the former president or any prominent supporters to add Mrs. Clinton to the ticket. Still, the idea of an Obama-Clinton ticket has been floated for months and some observers say it would be Mrs. Clinton's best chance to run again in 2016 if she isn't the nominee this time around. In an interview with Sky News, former President Jimmy Carter said he did not think Mrs. Clinton was achieving anything by staying in the fight. "I think not. But of course she has the perfect right to do so," he said while attending a literary festival in London. "I'm a superdelegate ... I think a lot of the superdelegates will make a decision quite, announced quite rapidly, after the final primary on June 3," he told Sky News. "I have not yet announced publicly, but I think at that point it will be time for her to give it up," Carter said. Democratic presidential candidate Obama is the front-runner. He holds a nearly insurmountable lead in delegates to the party's August nominating convention after months of contests that began in January. Mrs. Clinton has refused to quit until the last votes are cast and counted and the Democratic nominee is likely to be decided by the nearly 800 "superdelegates" -- members of Congress and other party insiders -- free to vote for whomever they want. The Democratic candidates need 2,026 delegates to be nominated to run against Republican John McCain in the November 4 U.S. presidential election. According to estimates by MSNBC, Obama now has 1,954 while Mrs. Clinton has 1,783. There are 86 delegates left to be chosen in the state-by-state contests. Meanwhile, the two Democratic rivals were campaigning in the Caribbean island of Puert Rico.