President Obama’s reelection campaign repeated its call for Mitt Romney to release additional tax returns Thursday, citing renewed interest in a tax shelter used by the Marriott hotel chain when Romney chaired the company’s audit committee in the 1990s.

In an op-ed published Wednesday by CNN, Peter C. Canellos, former chair of the New York State Bar Association Tax Section, and Edward D. Kleinbard, former chief of staff of Congress’s Joint Committee on Taxation, described Romney as “an executive who was willing to go to the edge, if not beyond, to bend the rules to seek an unfair advantage.’’


Canellos donated $2,300 to Obama in 2008.

He and Kleinbard noted that a federal appeals court ruled in 2009 that Marriott used “fictitious’’ losses to artificially reduce its taxable income during the period when Romney led the audit committee charged with ensuring tax code compliance. The scheme was known as “Son of BOSS.’’

Canellos and Kleinbard concluded that Romney showed “insensitivity to tax obligations’’ while on the Marriott board and wrote that the company’s engagement in Son of BOSS raises a question about Romney’s personal tax compliance: “Did he augment his wealth through highly aggressive tax stratagems of questionable validity?’’The Obama campaign has been posing the same question for months, as it has pressured Romney to make public more tax returns. Romney has released his 2010 return and an estimate for 2011 and has promised to share his complete 2011 return when it is filed. Presidential candidates are not required to release any tax returns, a point the Romney campaign makes frequently, though most major-party nominees in recent decades have made public more than two years of tax returns.The Romney campaign did not immediately respond to a request for comment on the Canellos and Kleinbard op-ed.Bloomberg News published an investigative report on Romney, Marriott and Son of BOSS in February. The Romney campaign declined to answer questions for that story.