Democrat Heidi HeitkampMary (Heidi) Kathryn HeitkampDoug Jones walks tightrope on Supreme Court nominee Red-state Dem tells Schumer to 'kiss my you know what' on Supreme Court vote Dem infighting erupts over Supreme Court pick MORE raised more than $710,000 in her first full quarter in the race to replace retiring Sen. Kent Conrad (D-N.D.).

Heitkamp, a former attorney general in North Dakota, had almost $850,000 in the bank as of the end of March, according to an advance copy of her first-quarter filing, obtained by The Hill. Heitkamp brought in $590,000 in contributions, and another $120,000 was transferred from other committees, including those that held joint fundraisers with Heitkamp.

Heitkamp's Republican opponent, Rep. Rick Berg, hasn't released his totals for January through March, which are due to the Federal Election Commission by Sunday. The freshman Republican had almost $1.4 million in his war chest at the end of 2011.

The first-quarter haul offered further evidence of fundraising success for Heitkamp, who raised about $450,000 in the last quarter of 2011 despite being in the race for less than two months.

Democrats are eager to hold on to Conrad's seat in a conservative-leaning state despite a difficult political climate for them in North Dakota, whose congressional delegation went from all Democrat to two-thirds Republican in 2010, the year Berg unseated former Rep. Earl Pomeroy (D).

Senate Democrats are defending 23 seats this year, compared to only 10 for Republicans, and are fighting for every seat to try and preserve their majority. If President Obama wins reelection, Republicans would need to pick up only four seats to win the Senate.

Heitkamp, who has wide name recognition across the state, has sought distance from Obama and Democrats on the campaign trail, positioning herself as an independent and pro-energy candidate unafraid to break with her party on key issues.

Heitkamp's campaign also plans to circulate a memo Friday outlining what it sees as a strong state of the race for Heitkamp. Little polling has been done in the race, but surveys by Democratic firms have suggested Berg could face a tougher path to the Senate than Republicans had expected.

"Our growing number of grassroots supporters, combined with our strong fundraising, will give us the resources we need to get our message out to North Dakotans," Heitkamp campaign manager Tessa Gould says in the forthcoming memo.