A longtime fundraiser for Rep. Charlie Rangel (D-N.Y.) will attempt to knock off one of Rangel’s Empire State colleagues next year, Rep. Sue Kelly (R-N.Y.).

Darren Rigger, a 35-year-old professional fundraiser making his first run for political office, is the first Democrat to enter the 19th district race.

Democrats have long hungered to field a tough challenger against Kelly, whose Hudson Valley district leans Republican but appears to be trending Democratic.

Whether Rigger fits the bill is hard to say; Republicans do not appear to be worried at this early stage.

“I find it hard to believe that one of Charlie Rangel’s people could get traction in Sue Kelly’s district,” said Carl Forti, communications director for the National Republican Congressional Committee.

Still, Rigger, who lives in and grew up in the Hudson Valley, believes that voters in the district, which gave President Bush a 9-point victory over Sen. John Kerry (D-Mass.) in the 2004 presidential election, are “frightened” by the conservative GOP agenda.

What’s more, Rigger is confident that the 2006 electoral terrain in New York works to his benefit. With Sen. Hillary Rodham Clinton (D-N.Y.) and the presumptive gubernatorial nominee, state Attorney General Eliot Spitzer (D), heading the ticket, Democrats are expecting of a big year statewide, and they are also hoping to win control of the state Senate. The counties north of New York City promise to be one of the state’s major battlegrounds.

“You are going to see an influx of tens of millions of dollars there just to get out the Democratic vote,” Rigger said.

Rigger also believes he is well-equipped to add to the spending spree in the district.

After graduating from Georgetown University’s School of Foreign Service in 1991, Rigger went to work at the Democratic National Committee under then-Chairman Ron Brown. He ultimately landed at the consulting firm headed by Democratic fundraiser David Jones, where his principal clients included Rangel, the Democratic Congressional Campaign Committee and then-House Minority Leader Richard Gephardt (D-Mo.).

Rigger has spent the past two years working for Rangel exclusively, but since deciding to challenge Kelly he has stopped working for the Congressman and has set up his own consulting firm, Spartan Strategies. His first two clients are Spitzer and a Hispanic voter registration drive sponsored by a leading New York labor union.

Although he doesn’t plan to start soliciting potential donors until September, Rigger said his fundraising experience will be a major asset — especially when raising money is one of the biggest hurdles that first-time candidates face.

“It just so happens that that’s what I do, every day, eight hours every day,” he said.

Rigger predicted that he would be able to raise $1 million and would match Kelly “dollar for dollar for fundraising.”

The 68-year-old Congresswoman raised $1.2 million to easily win a sixth term last year. She had a robust $347,000 in the bank on March 31.

An ability to raise and spend money is certainly something Democrats are seeking in a challenger to Kelly. Earlier this year, party leaders were talking to Connie Milstein, whose family owns one of the most powerful real estate development firms in the New York area, about running. But she is considered unlikely to enter the race.

Local Democratic officeholders are also likely to take a pass — unless there is evidence of a looming statewide Democratic sweep.

“The planets really are aligned for a different [Congressional] candidate” to win, Rigger said.