The Democratic Senatorial Campaign Committee (search) raised approximately $7 million in March, completing its best quarter of the campaign cycle, and has a war chest of roughly $6 million, officials said Wednesday.

Sen. Jon Corzine, D-N.J., said $11 million in receipts for the quarter show the committee has "made major strides in turning around our fund-raising operations" at the same time Democrats cite improved political prospects in key states.

"I think we've really energized our caucus. Their participation levels are up dramatically and we're starting to see some return on our direct mail and online fund raising," he said. The committee underwent a major staff shake-up in late January and early February.

The March total also was swelled by a major fund-raising event that 35 Democratic senators attended and brought in roughly $3 million.

Despite the gains, Democrats lag millions behind their Republican counterparts. The GOP committee reported cash on hand of $12.9 million a month ago and is expected to release updated figures for March in the next few days.

"I think ultimately we have a cash advantage that's going to allow us to have more of an impact on the competitive races that are in good territory for the Republicans to begin with," said Dan Allen, a spokesman for the Republican National Senatorial Committee (search).

Republicans hold a 51-48 majority in the Senate, with one Democratic-leaning independent. Additionally, five Democrats have announced plans to retire in southern states where President Bush figures to run well this fall.

Corzine said his party's chances have improved with the decision of Republican Sens. Don Nickles of Oklahoma and Ben Nighthorse Campbell in Colorado to retire.

"Colorado was a big shift because it was a place where we didn't feel optimistic and we were struggling, and you go from where you had a likely incumbent re-elected to a real opportunity" to take back the seat, he said. Democrats have rallied behind the state's attorney general, Ken Salazar, while Republicans failed to recruit Gov. Bill Owens and face a primary to pick a candidate.

In addition, polls point toward a competitive race in Oklahoma, where Nickles is retiring. There, surveys show Democratic Rep. Brad Carson (search) running well, and he will face the winner of a multicandidate Republican primary in late July.

Elsewhere, former Democratic Gov. Tony Knowles of Alaska is mounting a strong challenge to Sen. Lisa Murkowski (search), who was appointed to her seat and may face a primary rival. Democrats also hope to gain a seat in Illinois, where Republican Peter Fitzgerald is retiring.

Corzine also said Republicans face potentially debilitating primaries in North Carolina and South Carolina.