Tisei, the former Republican minority leader of the state Senate, paid no federal income taxes in 2006 or 2008, after reporting losses from his Lynnfield real estate firm and two rental properties, according to 10 years of tax returns he provided at the request of the Globe.

Tierney, meanwhile, has resisted disclosing any of his returns despite a public pledge to do so, numerous requests by the Globe, and new questions about whether he and his wife should have reported to the IRS at least some portion of the $200,000 that federal prosecutors say his wife received from a brother’s illegal gambling business, from 2003 to 2010.

Late Tuesday afternoon, after being pressed for weeks and being told the story would be published the next day, an attorney for Tierney offered to show the congressman’s tax returns to the newspaper in his office on Thursday morning — too late for the Globe to publish a newspaper story before the first scheduled debate Thursday afternoon. He did not promise to give the Globe copies of the returns so that they could be analyzed by outside experts.

In addition, as of Tuesday afternoon, the Tierney campaign had provided no evidence that the congressman has ever publicly released his taxes, despite a statement from a spokeswoman to the contrary and Tierney’s own claim during a July 3 news conference.

“We’ve released our tax returns in every election,” Tierney said then. “We’ll release the same ones we release all the time.”

Tierney, a Salem Democrat seeking his ninth term representing the Sixth Congressional District, has said the money his wife received from her brother, Robert Eremian, was a gift and therefore exempt both from federal taxation and requirements that he publicly disclose the source of the money.

Meanwhile, hehas enlisted well-known libel attorney Howard M. Cooper in an effort to dissuade the Globe from publishing a story exploring whether 2011 court testimony by Tierney’s wife, Patrice, indicates the money was taxable income, not a gift. Four independent tax experts, including two willing to be quoted by name, told the Globe that the money from her brother seemed more like income because she said she performed services in exchange for the funds. As income, it would be subject to taxes.

Tierney’s congressional and campaign staffs refused to discuss issues related to Tierney’s taxes for almost three weeks and initially declined to release his returns, saying the Globe had not shown “good faith,” in the words of Tierney’s campaign manager.

“We do not take your request for tax returns as made seriously or in good faith, and we will certainly not provide you with material for you to further misconstrue in an effort to publish a false story,” Tierney campaign manager Matt Robison said in a statement to the Globe. “If you are interested in writing a different story about some other aspect of the returns which does not involve a false and misleading allegation, then Congressman Tierney will of course reconsider providing his returns to you.”

In addition, an attorney representing Patrice Tierney said issues related to the money from her brother had been investigated by the IRS previously and the agency brought no charges, though the probe predated Patrice Tierney’s 2011 court testimony.

The combative campaign to represent the Sixth District, which stretches from Lynn to the New Hampshire border and includes the cities of Salem and Peabody, is one of the most competitive in the country, featuring a barrage of harsh negative ads.

Recently, a super PAC with ties to the Republican House leadership unleashed a television ad claiming that Tierney “knew everything” about the illegal, Antigua-based gambling enterprise run by his brother-in-law Robert Eremian. Tierney has said he is guilty only of standing by his wife, who spent a month in federal prison in 2011 after pleading guilty to “willful blindness” while managing a multimillion dollar bank account for her brother and helping him file false tax returns.