Rep. Dan Lungren raised $237,000 in the last quarter.
Democrats have an early fundraising edge in six closely-watched 2010 House rematches in Arizona, California, Kentucky, New Hampshire, North Carolina and Washington.
Rep. Rick Larsen (D-Wash.), who won one of the closest races of last cycle, raised nearly $300,000 in the second quarter and had more than $500,000 in cash on hand on June 30.
"The strength of this early support is proof that we're working hard and focused on the right things: creating jobs, growing our economy, and protecting Social Security and Medicare in a fiscally responsible way," said Larsen, who is running for a seventh term in northwest Washington. "I am thankful for those that have shown their support to my campaign."
Larsen's strong start puts his 2010 challenger, Republican John Koster, well behind in the money race. Koster, who came within 7,000 votes of Larsen last year, announced he was running for Congress in early May, but did not file his campaign paperwork until June 20.
With his first fundraiser scheduled for early July, Koster had raised just $15,000 and had just $7,000 in the bank by the end of June.
Kentucky Rep. Ben Chandler (D), a perennial GOP target, pulled in $229,000 in the second quarter. However, Lexington Attorney Andy Barr, who lost to Chandler by only 647 votes in 2010, brought in nearly $200,000 in the three weeks since announcing his campaign on June 9.
The Chandler-Barr rematch is expected to be among the top House races of the cycle.
"I am honored to have earned so many strong supporters so early in my campaign," Barr said in a statement.
Chandler had $561,000 in cash on hand at the end of June, while Barr had $203,000.
Vulnerable North Carolina Rep. Mike McIntyre (D), who faces the prospect of running in a more Republican district in 2012, raked in $286,000 in the second quarter and had $377,000 in cash on hand at the end of June.
Retired Marine Corps officer Ilario Pantano, McIntyre's only declared opponent, raised just $53,000 in the second quarter and had a meager $20,000 in cash on hand at the end of June. Pantano lost to McIntyre by seven points in 2010.
Notably, Pantano is not part of the National Republican Congressional Committee's Young Guns program that was announced this week, and other contenders are expected to run against the vulnerable Congressman. The Republican-controlled North Carolina Legislature is likely to release a new draft version of a Congressional redistricting map on Monday, according to local media reports.
In Arizona's 1st district, Rep. Paul Gosar (R) was outraised in the second quarter by former Rep. Ann Kirkpatrick (D), whom Gosar unseated last year. Kirkpatrick announced raising $240,000 from April to June, which nearly matches Gosar's total for the year.
Gosar brought in $170,000 last quarter, which was nearly double what he took in from January to March. He ended June with $138,000 in the bank compared to Kirkpatrick's $216,000.
Former Sen. Scott Brown, R-Mass., candidate for U.S. Senate in New Hampshire, holds his hand over his heart during the singing of the national anthem as he waits to take the stage for his town hall campaign rally with Sen. John McCain at the Pinkerton Academy in Derry, N.H., on Monday, Aug. 18, 2014.