Democrat Michelle Nunn raised more than $1.6 million in campaign donations for her U.S. Senate campaign in the last three months of the year, ratcheting up the pressure on the crowded field of Republicans seeking to keep the prized seat in GOP hands.

The figures, which come on the heels of Nunn's $1.7 million take during the first three months of the campaign, come days after Democratic state Sen. Jason Carter said he's raised $1.3 million in his bid to oust Republican Gov. Nathan Deal.

Nunn’s campaign said Sunday it raised a total of about $3.3 million from more than 10,000 donors since she entered the race in July. The line-by-line details of her supporters won’t be available until later this month, but Nunn’s donors include former U.S. Sen. John Warner, a Virginia Republican.

“This campaign is about doing things differently and the diverse group of people joining our effort proves it,” said Nunn, who said her supporters want to “replace the political bickering and gridlock in Washington with pragmatism and problem-solving.”

Nunn, a nonprofit executive who recently led the Points of Light volunteer organization, has never held public office before. But her bid has attracted national attention because of her pedigree as the daughter of former U.S. Sen. Sam Nunn. Along with Carter’s gubernatorial run, she has buoyed her party’s hope of forging inroads in a state dominated by Republicans.

A strong fundraising report by Nunn was important to underline her status as a top-notch contender in the wide-open race to succeed U.S. Sen. Saxby Chambliss. With support from powerful Democrats in Atlanta and Washington, she's the front-runner in her party's May 20 primary in a field that includes Dr. Branko Radulovacki and former state Sen. Steen Miles.

But five well-known Republicans are competing for their party’s nomination and the winner is expected to have formidable resources as the GOP seeks to regain control of the Senate. State Republican chair John Padgett often invokes Nunn’s candidacy during stops around the state to encourage donors to dig deeper into their pockets.

“I’m here to tell you this is not a purple state,” Padgett said at a recent event. “And the Georgia GOP is not going to fall down on its duty to you and the rest of the country and let this state turn into a purple state.”