Mark Green has lost campaigns for U.S. Senate (twice), mayor (once), Congress (once), and, just last year, state attorney general (once). Each time, he has bounced back. And now he seems poised for another comeback, courtesy of his older brother, multimillionaire landlord Stephen Green, who is poised to buy Air America Radio in a deal that would save the left-wing network from bankruptcy and catapult Mark Green back into the political fray.

Comedian and author Al Franken, the name and personality behind Air America Radio, said yesterday that his last show on the struggling network would be February 14. Presumably, Mr. Franken will leave his daily program, “The Al Franken Show,” to prepare his own campaign for a U.S. Senate seat in his home state of Minnesota, where Senator Coleman, a Republican, comes up for re-election in 2008. The seat was formerly held by the late Senator Wellstone, a Democrat.

“The network will be in good hands with the Green brothers: Mark, my friend for years and a committed liberal who understands the mission of Air America as well as anyone, and his brother Steve, who is very wealthy,” Mr. Franken said in a statement yesterday.

Sources familiar with the deal suspect that perennial Democratic candidate Mark Green will feature prominently on the radio network. He served as a guest host of an Air America program, “Politically Direct,” earlier this month. Earlier in his career, he regularly debated William F. Buckley Jr. on PBS’s “The Firing Line.” Mr. Green, who was elected and served as the city’s public advocate, has also appeared as a regular panelist on NY1’s “Wiseguys” segment with Mayor Koch and Senator D’Amato, a show in which his main role appeared to be to exasperate Mr. Koch.

After losing in the primary election for New York attorney general to Andrew Cuomo, Mark Green said at that time he would not again seek political office. Mr. Green lost a close race to become mayor of New York in 2001 to Michael Bloomberg, also lost two races for US Senate in 1986 and 1998, and a run for the House of Representatives in 1980. He was twice elected as the city’s public advocate.

Yesterday, Mr. Green said the time is ripe for a recreation of the left-wing radio network. “With the Democratic take-over of the 110th Congress and prospects in the next presidential election, it’s the perfect time for Air America 2.0. If progressive values were a stock, now is the time to buy,” he said in a statement.

A lawyer who has worked for Stephen Green, Robert Ivanhoe of the firm Greenberg Traurig, said Air America would provide a good platform for Mark Green.

“Steve has been his biggest supporter — to say the least — for a very long time,” Mr. Ivanhoe said. “He certainly has the means to do things to continue to support his brother’s pursuits in the political and public arena.”

“Mark and Al Franken are very close. Maybe there is a line of secession,” Mr. Ivanhoe added.

A political consultant, George Arzt, said Mark Green would likely enjoy more prominence leading Air America than he would have had as New York attorney general. “It’s a perfect forum for Mark. He is opinionated, and can discuss any issue, foreign and domestic, with expertise,” Mr. Arzt said. “I don’t know if it’s a great investment for Steve, but I’m not a businessman.” Financial problems and mismanagement dogged Air America Radio since its launch in March 2004, and its owners filed for bankruptcy protection in October. In 2005 and 2006, the radio network is said to have lost more than $30 million. Last summer, as part of the city’s department of investigation’s probe into the Gloria Wise Boys & Girls Club regarding improper expenditures of city funds, the agency discovered that the club had transferred $875,000 to Air America in the period leading up to the network’s launch in March 2004. A co-founder of Air America, Evan Montvel Cohen, had simultaneously served as development director for the Gloria Wise Boys & Girls Club, and Mr. Cohen later told The New York Sun that he arranged the transfer of $875,000 to the radio network from the club. Stephen Green has been a prime fundraiser for his brother Mark’s political campaigns. He founded S.L. Green Real Estate in 1980 and now serves as chairman of SL Green Realty, the publicly traded real estate investment trust whose holdings include 28 New York office properties. Stephen Green’s shares in S.L. Green were yesterday valued at $20.9 million, though he realized a much greater fortune when he took the venture public. In a statement, Stephen Green said he was purchasing majority ownership in the fledgling radio network to transform it into a money-making enterprise.

“First, we’ll stabilize its finances. Second, we’ll build on its line-up to assure the best radio talent possible, since in the long run content is king. And third, we’ll extend this special brand by partnering with other platforms beyond radio to make sure that Air America’s content reaches the wide audience it deserves,” Stephen Green’s statement said.

No terms of the sale agreement were disclosed. Any sale would have to be approved by the bankruptcy court.