Republican House challengers outraised vulnerable Democratic incumbents in six races in the third quarter of the year, another reason for GOP optimism as Republicans seek to regain lost ground in Congress in 2010.

Democratic challengers outraised Republican Members in three races in the same time period, according to a Roll Call analysis of 50 of what are expected to be the most-contested seats in the 2010 election.

Former Rep. Steve Pearce, who left his New Mexico House seat to run for Senate in 2008, and Tennessee farmer and gospel singer Steve Fincher led the way for Republicans, turning in big fundraising quarters that eclipsed their Democratic rivals, freshman Rep. Harry Teague (N.M.) and 11-term Rep. John Tanner (Tenn.), respectively.

Pearce outraised Teague by about $250,000 despite a very respectable quarter by the Democrat — $508,000 to $257,000 — in his first quarter since joining the race. Teague still had an almost $300,000 cash-on-hand edge over Pearce as of Sept. 30 in what is likely to be one of the most competitive, and most expensive, races in the country next year.

Fincher, meanwhile, topped Tanner’s receipts by $246,000, largely due to an underwhelming $62,000 fundraising quarter for the incumbent. Tanner’s office said last week that he is still sitting on about $1.4 million in cash on hand as of Sept. 30 and said his focus over the summer was not on fundraising but on “talking with as many west and middle Tennesseans as possible about how to help create private-sector jobs in Tennessee and learning what works in our health care system and what is broken.—

The Democrats’ best challenger showing came in California’s 3rd district, where two party hopefuls both easily topped Republican incumbent Dan Lungren. Physician Ami Bera kept up his blistering fundraising pace in the third quarter, raising $337,000, almost all of it from individual donors.

The one-time chief medical officer for Sacramento County made a splash in July when he announced he had raised more than $288,000 in his first quarter of fundraising, ranking him seventh among House challengers nationally.

Bera faces a primary contest with another well-funded Democrat, Bill Slaton, director of the Sacramento Municipal Utility District. Slaton reported $253,000 in receipts, including a $175,000 loan from the candidate.

Bera ended the quarter with $586,000 in cash on hand, making him one of the few challengers to also boast a cash lead over an incumbent (Lungren finished September with $444,000 in the bank). Another is Democrat Suzan DelBene, who reported $256,000 in receipts to $222,000 for incumbent Dave Reichert (R-Wash.) and has nearly double Reichert’s cash on hand. DelBene, a former Microsoft executive, has kicked in $489,000 of her own money.

In other races where GOP challengers trumped Democratic Members in third-quarter fundraising, the party was boosted by self-funders. That includes North Carolina’s 8th district, where freshman Larry Kissell (D) pulled in just $84,000 for the quarter, compared with $103,000 for retired Army colonel and defense industry consultant Lou Huddleston and $312,000 for Army veteran and military equipment entrepreneur Tim D’Annunzio. D’Annunzio’s total includes $300,000 of his own funds.

In New York’s 19th district, second-term Rep. John Hall (D) was also outdone by two GOP challengers — state Assemblyman Greg Ball and ophthalmologist Nan Hayworth. Hall raised $133,000 to $196,000 for Ball and $318,000 for Hayworth, who just joined the race and started off with $150,000 from her own pocket.

Freshman Rep. Glenn Nye (D) faces two self-funders in his race in Virginia’s 2nd district. Republican businessman Ben Loyola loaned his campaign $500,000 in this year’s third quarter, giving him $548,000 in total receipts. Another challenger, car dealership owner Scott Rigell, gave personal loans or contributions to his campaign totaling $226,000 — almost half of his campaign’s $453,000 in total receipts. Nye pulled in $280,000 in the third quarter and maintains a cash-on-hand advantage over both prospective opponents.

Republican Steve Stivers, who is gearing up for a rematch with Mary Jo Kilroy (D-Ohio), edged her by $37,000 in third-quarter receipts. Kilroy still enjoyed an overall financial cushion, with nearly $500,000 in the bank compared with $266,000 for Stivers.

Among the vulnerable incumbents who looked strong financially vis-à-vis their challengers were Rep. Joe Wilson (R-S.C.), whose “You lie!— outburst during President Barack Obama’s September address to a joint session of Congress earned him $2.7 million for the quarter; freshman Rep. Jim Himes (D-Conn.), who continues to pile up a massive war chest in the 4th district, with $379,000 in receipts in the third quarter; Rep. Patrick Tiberi (R-Ohio), who doubled-up Democratic challenger Paula Brooks in receipts and had $930,000 in the bank; and Rep. Chet Edwards (D-Texas), who raised nearly ten times his nearest challenger in receipts in the 17th district.