US election 2012: Mitt Romney under mounting pressure to release tax returns Conservative commentators said Mr Romney refusal to release more than two years of tax returns - 2010 and 2011 - was poisoning the campaign. He should release the tax returns tomorrow. It's crazy," said Bill Kristol, the editor of the conservative Weekly Standard, on Fox News. You have got to release six, eight, 10 years of back tax returns. Take the hit for a day or two. While Mr Romney spent the weekend at his family £5.5 million lakefront home in New Hampshire, his advisers took to the airwaves to try and wrestle back control of the debate which they admitted was being hijacked by negative Obama campaign advertising. "They want to talk about anything other President Obama's dismal record on the economy, and it's working," Ed Gillespie, a senior Romney adviser, told CNN. Faced with poor economic numbers, the Obama campaign has moved aggressively to try and define Mr Romney out of the race before the final stretch has even begun, characterising him as an elitist and a profiteer whose business career at Bain Capital put self-enrichment before job creation. Independent media monitors say that the blitz of negative television advertising in key swing states such as Ohio, Florida and Iowa has already reached levels that were not seen until September during the 2008 campaign. Mr Romney's campaign have tried to fight back, calling Mr Obama "a liar" and accusing the president on reneging on his 2008 message of "hope and change," but have conspicuously failed to force the issue of Mr Romney's tax returns off the agenda. The Obama campaign has redoubled its attacks, releasing a new campaign ad using a recording of Mr Romney singing an off-key rendition of "America the Beautiful" over pictures of a fluttering Swiss flag and palm-fringed beaches of Bermuda and the Cayman Island. Mr Obama's senior campaign adviser, David Axelrod, then pressed home the message on Sunday, accusing Mr Romney, whose personal fortune is estimated at £160m, of using "every conceivable" tax shelter and loophole, including a Swiss bank account to reduce his liabilities. "Is he the guy who is going to clean up our tax code and make it advantageous to average taxpayers and the country, or is he going to look at it through the lens of his own experience?" said Mr Axelrod on CNN, defending the relevancy of his campaign strategy.