Chicago – from www.chicagotribune.com – U.S. Rep. Jesse Jackson Jr.’s long-held desire to become mayor of Chicago ran smack into the controversy over his last hot pursuit of a political prize when he was forced Tuesday again to deny allegations that he sought to buy a U.S. Senate seat.

Adding to the troubles are revelations that a longtime political supporter told federal investigators he paid to fly a female “social acquaintance” of Jackson’s to Chicago at the congressman’s request.

Jackson issued a written apology to voters that lacked specifics about the woman but acknowledged he disappointed some supporters. His wife, Ald. Sandi Jackson, issued her own statement, saying the couple had for months been trying to deal quietly with the “painful and unfortunate situation.”

The Jacksons sought to portray a united front Tuesday night, showing up together at a fundraiser in Hyde Park for Sandi Jackson, who is seeking a second term as 7th Ward alderman. They declined to answer questions heading into the closed-door event.

It may have been the rockiest moment yet for the political couple, who have enjoyed days of speculation that either one might seek to replace outgoing Mayor Richard Daley in the February 2011 election.

Amid that hopefulness, the congressman had avoided answering detailed questions about allegations that he was behind a bid to raise $1 million or more for ex- Gov. Rod Blagojevich in exchange for being appointed to the Senate seat vacated by President Barack Obama.

But on Tuesday, Jackson found the Senate controversy rekindled in the form of new allegations, first reported in the Chicago Sun-Times, by an Indian-American businessman who raised money for both Jackson and Blagojevich.

The businessman, Raghuveer Nayak, told federal investigators the congressman asked him to raise campaign money for Blagojevich in hopes that the then-governor would appoint Jackson to the Senate seat vacated by Obama, sources familiar with the investigation told the Tribune.

The allegations tracked with 2008 reports by the Tribune, and disclosures at Blagojevich’s recent corruption trial, that Nayak and a fellow Indian-American businessman had agreed to help Jackson’s chances of replacing Obama by raising money for Blagojevich.

Jackson disputed the claims in his written statement Tuesday, saying he already has spoken to federal authorities about them, and noting that he has not been charged with any crimes.

“The very idea of raising millions of dollars for a campaign other than my own is preposterous,” Jackson said. “My interest in the Senate seat was based on years of public service, which I am proud of, not some improper scheme with anyone.”

In his statement, Jackson did not deny Nayak’s allegation that he paid to fly a female “social acquaintance” of Jackson from Washington to Chicago at the congressman’s request.

“The reference to a social acquaintance is a private and personal matter between me and my wife that was handled some time ago. I ask that you respect our privacy,” Jackson said in the statement.

“I know I have disappointed some supporters, and for that I am deeply sorry. But I remain committed to serving my constituents and fighting on their behalf.”

According to sources, Nayak told authorities he twice paid for travel for the woman. Both Nayak and the woman were questioned by investigators, the sources said, and Nayak provided documents proving the purchase of airline tickets to corroborate his account.

Nayak’s lawyer, Thomas McQueen, confirmed his client had met with authorities and provided documents in response to a grand jury subpoena.

The woman, who lives in Maryland, outside of Washington, could not be reached for comment. She works as a hostess at Ozio Restaurant & Lounge, billed as a cigar and martini lounge. According to federal campaign reports, Jackson has spent $31,500 out of his campaign fund at the restaurant on fundraisers as well as lunch and dinner meetings.

Ald. Jackson’s spokeswoman, Keiana Barrett, declined to answer most questions but said the Jacksons were working on their marriage.

Nayak, who made a career running Chicago-area surgery centers, was not called as a witness at Blagojevich’s trial. Sources said federal authorities have been questioning some of Nayak’s business associates about how the surgery centers were run.

Nayak has not been charged with wrongdoing.

Though the latest allegation deals with a meeting that occurred between Nayak and Jackson Oct. 8, 2008, in Washington, prosecutors alleged at Blagojevich’s trial that Jackson also met with Nayak and another Indian-American businessman Oct. 28, 2008, to discuss fundraising.

Jackson said last week that though he was at that meeting, the two men sometimes spoke in Hindi, and he was unaware of the promise of campaign cash for Blagojevich on Jackson’s behalf. Some promises of cash to Blagojevich were as high as $6 million, according to trial testimony.