There’s a conundrum in Roll Call’s list of the 10 House Members who appear the most vulnerable to defeat in their 2010 re-election contests.

Nine of the 10 are Democrats. But that is because their party did so exceptionally well in the 2006 and 2008 elections.

The Democrats would have built a solid House majority just by picking the “low-hanging fruit— — defeating Republican incumbents or winning GOP open seats in districts that had already been trending Democratic or that swung sharply as public approval of President George W. Bush and Congressional Republicans plunged.

But to build the big majority that they currently enjoy, the Democrats had to push into some strongly Republican territory. And just as Bush played a big role in the Democratic sweeps of the past two cycles, you can expect that President Barack Obama and Speaker Nancy Pelosi (D-Calif.) will play starring roles in TV attack ads next fall targeting vulnerable Democrats.

Of the nine Democrats on this list, six represent districts that voted for Sen. John McCain (R-Ariz.) over Obama for president in 2008. Freshman Reps. Bobby Bright (D-Ala.) and Walt Minnick (D-Idaho) each represents a district that favored McCain by a margin of 26 points.

The other three most vulnerable Democrats are from districts that swung to Obama but favored Bush at the top of the GOP ticket in 2004.

If, as Republicans argue, 2010 will be a more favorable year for their party, several at-risk Democrats will have their tenures cut short. Even if the Democrats regain some momentum, it wouldn’t be surprising if some of these Members get sent packing because history is not on their side: The party in the White House almost always loses seats in the midterm elections.

Nonetheless, the one Republican on the list, freshman Rep. Anh “Joseph— Cao (La.), may be the single-most vulnerable incumbent. Cao’s 2008 victory, in a majority-black Democratic stronghold based in New Orleans, still looks implausible. But few challengers have the benefit of an opponent as damaged as was Cao’s: Then-Rep. William Jefferson (D), who ran while under indictment on federal corruption charges, which he was convicted of after his defeat.

Members are listed alphabetically and not ranked in order of vulnerability.

Bobby Bright (D-Ala.)

One of the first traditional conservative Democratic strongholds to go Republican in the 1960s, southeastern Alabama’s 2nd district had long been represented by Rep. Terry Everett (R). But Everett retired in 2008, and Bright — the conservative mayor of Montgomery who has personal ties to the district’s rural areas ­­— gave the Democrats a chance of a lifetime. Still, district voters showed their Republican side as they favored Sen. John McCain (Ariz.) for president by a huge margin, even as they elected Bright to the House by less than 1 point. The GOP is touting Montgomery City Councilwoman Martha Roby as a top recruit.

Anh “Joseph— Cao (R-La.)

Cao has tried to convince his overwhelmingly Democratic constituency that he is an independent, moderate Republican. Congressional Quarterly found that through August, Cao sided with most Republican colleagues against most Democrats on just 58 percent of party-line votes, the lowest “party unity— score among GOP Members. And Cao, a member of the district’s minority Vietnamese-American community, has focused heavily on the problems of those affected by Hurricane Katrina, which most afflicted the district’s large African-American population. But this is a district that went 75 percent for Barack Obama in the 2008 presidential contest — and Cao defeated Jefferson, the scandal-plagued incumbent who stood accused of wrapping thousands of dollars in ill-gotten gains in foil and hiding it in his freezer. State Reps. Cedric Richmond and Juan LaFonta are running for the Democratic nomination.

Steve Driehaus (D-Ohio)

Driehaus won by 5 points in 2008, after Democrats had failed in a series of attempts to oust then-Rep. Steve Chabot (R) from the Cincinnati area’s politically competitive 1st district seat. But Chabot is seeking a rematch, spurring a targeted take-back try by national Republicans. Though Driehaus had a reputation as a fiscal conservative as a state House Member, the GOP is branding him too apt to support President Barack Obama’s agenda, citing his vote for the economic stimulus bill. But Driehaus beat Chabot by tying him closely to former President George W. Bush, and the ex-incumbent’s ability to come back will be affected by whether Bush is still salient to voters in November 2010.

Alan Grayson (D-Fla.)

The GOP argues that Grayson, who has quickly become a lightning rod, is far too liberal for this swing district. But unlike many Democratic freshmen from dicey districts, who are showing their centrist stripes, Grayson has adopted the old maxim that the best defense is a good offense. Grayson took to the House floor recently to declare that the Republican plan for addressing the nation’s health care issues was to “don’t get sick— and, if you get sick, to “die quickly.— While Republicans say comments such as this provide the ammunition that they need to beat Grayson in 2010, they have struggled at candidate recruiting, with a series of well-known prospects turning them down. The ability of Grayson, a wealthy lawyer, to self-fund — he put almost $3 million into his 2008 race — may be putting off potential challengers.

Mary Jo Kilroy (D-Ohio)

Kilroy has two big problems heading into her 2010 campaign. The first is that she faces a rematch with Steve Stivers, who was a state Senator when he ran in the 2008 open-seat race and fell just a hair short. Kilroy’s other problem is that the Columbus-area 15th district is split almost down the middle between the parties. Republicans contend that Kilroy’s early House record as a Democratic loyalist is unsustainable in this swing district. But Democrats are moving assertively to shore her up, with Vice President Joseph Biden visiting the district a week ago.

Frank Kratovil (D-Md.)

Kratovil will have his hands full defending his seat in Maryland’s difficult-to-navigate 1st district, which includes the entire conservative-leaning Eastern Shore as well as parts of suburban and exurban Baltimore. A former local prosecutor from the Eastern Shore, Kratovil faces a likely rematch with state Sen. Andy Harris, a Baltimore-area physician, whom he beat by less than 1 point. He got that matchup only because the conservative Harris beat moderate Rep. Wayne Gilchrest in the 2008 GOP primary. Gilchrest ended up endorsing Kratovil for the fall race. The district’s voters split their tickets to favor Sen. John McCain (R-Ariz.) for president by 18 points. But Kratovil should get a boost from the interest in his race of the two Maryland Democrats in House leadership: Majority Leader Steny Hoyer and Democratic Congressional Campaign Committee Chairman Chris Van Hollen.

Betsy Markey (D-Colo.)

The sprawling 4th district still has a rural West feel, but Democratic voters in places such as Fort Collins and Greeley make it less of a Republican stronghold than it long was: Sen. John McCain (R-Ariz.) edged Barack Obama there by just 1 point. That helped Markey — a high-tech businesswoman and former Senate aide — make a case that three-term Rep. Marilyn Musgrave (R), who had focused heavily on social issues such as opposition to same-sex marriage, was too far right. Nonetheless, Markey’s margin of more than 12 points over Musgrave seems outsized for this district, and the Republicans are touting state House Minority Whip Cory Gardner as a strong recruit.

Walt Minnick (D-Idaho)

Like Cao in Louisiana, Minnick’s 2008 win in an Idaho Republican stronghold would have been a shocking upset — had it not been for a deeply flawed incumbent. Then-Rep. Bill Sali (R) didn’t have a corruption problem, but his hard-line conservatism and his reputation as personally abrasive cut deeply into his support among the district’s Republican base. So Minnick, after winning by 1 point in a district dominated by Sen. John McCain (R-Ariz.) for president, now is one of the most vulnerable Democratic incumbents. Yet the former forest products industry executive casts himself as fiscally conservative and a strong supporter of gun owners’ rights, and his voting record thus far gives him a solid claim on political independence: His 40 percent party unity score through August was the lowest of any House Member in either party. Minnick also has a big early fundraising lead over the two active GOP contenders, retired Marine Corps Maj. Vaughn Ward and state Rep. Ken Roberts, who chairs the state House majority caucus.

Tom Perriello (D-Va.)

Virginia’s 5th district is another of those that looked firmly in Republican control until recently. Even in the strong Democratic year of 2006, then-Rep. Virgil Goode (R) won a sixth term by a solid 20-point margin. And Perriello, a first-time candidate who founded a human rights nonprofit group, seemed an odd fit for a district that has a liberal bloc in and around Charlottesville (home of University of Virginia) but covers mostly conservative territory to the south — the area commonly known as Southside. But Perriello organized and started raising money early, and he was helped by a strong turnout for Barack Obama that shrunk the GOP’s presidential margin in the 5th from 13 points in 2004 to 3 points in 2008. Still, Perriello won by just 0.2 point. There are other Republicans in the race, but state Sen. Robert Hurt (R) is the likely nominee to take him on next year.

Harry Teague (D-N.M.)

Teague, the owner of an oil-well services company and a former county commissioner, positioned himself well as a conservative-leaning Democrat in 2008. He ended up winning by 12 points in the race for the seat that then-Rep. Steve Pearce (R) left open to run for Senate. But any hope that Teague had for a typical incumbent’s advantage evaporated when Pearce — trounced in the Senate contest — announced he would seek to reclaim his old 2nd district seat. Republicans have wasted no time trying to portray Teague as out of step with the district and too beholden to Speaker Nancy Pelosi (D-Calif.), and they have made hay of the freshman’s risky vote for the cap-and-trade bill, which Republicans describe as harmful to the economy. But Teague’s $936,000 in campaign receipts through Sept. 30 to the later-starting Pearce’s $508,000 show that he is ready for the fight.