Cory Alexander, former chief of staff to House Majority Leader Steny Hoyer (D-Md.) and one of K Street’s most eligible Democrats, is off the market.

Three sources confirmed that Alexander, most recently with Fannie Mae, has reached a deal to be a top in-house lobbyist for UnitedHealth Group, a $75 billion a year company that ranks 25 on the 2008 Fortune 500 list.

Alexander, who declined comment, will serve as deputy head of corporate government affairs at UnitedHealth. He will oversee and direct the company’s federal government relations operation and strategy, reporting to Jud Sommer, who is senior vice president for government affairs. He also will have a senior role in state government relations and in the company’s internal business strategy on regulatory issues.

“Cory is a fabulous hire who will really position us as we head into this important year with respect to health care issues,” Sommer said.

Alexander’s salary is likely to be north of $750,000, perhaps approaching the seven-figure range.

“Cory is probably one of the top Democrats — if not the top Democrat — on the market,” said fellow Democratic lobbyist Steve Elmendorf, whose firm Elmendorf Strategies represents UnitedHealth. “He will be in a position not just to shape lobbying strategy, but corporate strategy.”

Alexander’s position is a newly created post at the company.

“It’s a sign that companies are realizing that they need to up their Democratic strategic capability,” Elmendorf said.

Democratic staffers on the Hill similarly lauded Alexander’s new post.

“Landing Cory Alexander is a big coup for UnitedHealth,” said a chief of staff to a senior centrist Democrat involved in health care reform policy. “They are a big, strong company with a need to ramp up their presence and approach to the Obama administration and Capitol Hill. Cory will be one of the best at doing this in the coming years.”

After leaving Hoyer’s staff in March 2006, Alexander joined the in-house team at former lobbying powerhouse Fannie Mae, where he led the shop’s Democratic team with both the House and Senate. But the government-sponsored company’s influence diminished as it was hit by the mortgage crisis. And as the federal government took over greater control of the ailing enterprise, it forced Fannie to stop all lobbying efforts.

Several sources said that Alexander, 36, entertained multiple offers, mostly from contract lobbying firms, and had come close to a lucrative deal with General Electric. Some Democrats also suggested Alexander — who is still close to Hoyer and incoming White House Chief of Staff Rahm Emanuel — was considering returning to the Hill.

Even at a time when senior Democrats are very much in demand in the downtown corridor, Alexander stands out. He has recent Congressional leadership experience and a private-sector background — a combination many say allows him to command a high salary.