Few House members seeking re-election next year will be as vigorously targeted for defeat by the opposing party as freshman Reps. Walt Minnick of Idaho and Anh “Joseph” Cao of Louisiana.

Minnick is a Democrat who represents a rural and strongly conservative district that gave Barack Obama just 36 percent of the vote in the 2008 presidential election. Cao is a Republican from a heavily black district in and around New Orleans that gave just one in four of its votes to GOP presidential nominee John McCain .

After defeating flawed incumbents in the 2008 election, Minnick and Cao will be campaigning for re-election on their efforts in Congress as first-term lawmakers. That will likely be an easier thing for them to do if they compile and highlight independent voting records that distinguish them from their national parties, which are not popular in their districts.

And according to a Congressional Quarterly study of House members’ voting behavior at the midpoint of 2009, Minnick and Cao are making serious attempts to differentiate themselves during their first months in office. Each broke with his party more frequently than other members on legislative votes that divided the House mainly along partisan lines.

On the 255 roll call votes that pitted most House Democrats against most Republicans — which CQ brands as “party unity” votes — Minnick backed the consensus Democratic position just 40 percent of the time. Cao agreed with the position held by most fellow Republicans 63 percent of the time.

The study shows that Democrats overall are highly unified, with a median party unity score of 98 percent. But party unity scores below the Democratic norm are common among junior members, such as Minnick, who face difficult challenges stemming from their districts’ usual partisan orientation.

Of the 20 lowest-scoring Democrats in the party unity study, 16 are serving either their first or second terms, and the same number represent districts that voted for McCain over Obama for president in 2008.

The Democratic Party includes “independent voices who put the families of their districts first,” said Ryan Rudominer, a spokesman for the Democratic Congressional Campaign Committee. “Unlike the Republicans, the Democrats have a big tent where a diversity of viewpoints is welcomed.”

An image of political independence is a necessity for lawmakers like Minnick, who cannot afford to be closely identified with the national Democratic Party in a district that Republicans have represented for 38 of the past 42 years.

Minnick most recently bucked the Democratic leadership by voting against a broad energy policy bill (HR 2454), which is intended to address climate change but which opponents claim is too economically burdensome. He earlier went against the Democratic tide by opposing the economic stimulus measure that President Obama signed into law in February (PL 111-5) and the fiscal 2010 budget resolution (S Con Res 13).

“I’m a fiscally conservative businessman ... and I look at things through the lens of my experience, with input from my state. My district is conservative,” said Minnick, who already has to steel himself for a challenge in his 2010 race from Vaughn Ward, an Iraq war veteran, who has announced his candidacy for the Republican nomination.

“We want to vote for what’s best for the country and what’s best for my district, regardless of party position,” Minnick added. “We look at every bill very seriously from that perspective.”

Democratic leaders are mindful of the politics of Minnick’s voters and tolerate his voting independence. And with control of 257 House seats, Democrats can prevail on votes even if as many as a few dozen members vote with Republicans.

New York Democratic Rep. Eric Massa , elected last year to represent the state’s conservative-leaning Southern Tier, has a 91 percent score. Tom Reed, the Republican mayor of Corning, on Wednesday announced a 2010 challenge to Massa.

You Can GOP Your Own Way Too

Unlike their Democratic colleagues, most of the new House Republicans hail from politically safe GOP strongholds and have higher party unity scores. Of the 20 lowest-scoring Republicans, only Cao and fellow freshman New Jersey Rep. Leonard Lance are serving either their first or second terms.

Because of his district’s strongly Democratic-leaning demographics, Cao is the most vulnerable House member in either party. He sided with Democrats and against Republicans in voting to expand children’s health insurance programs and federal hate crimes laws (HR 1913). He was one of five Republicans who voted last month for a war supplemental spending law (PL 111-32) advocated by Obama.

Several contrarian Republicans are thinking about seeking statewide office: Mark Steven Kirk of Illinois (76 percent), who is weighing a run for senator or governor; Michael N. Castle of Delaware (75 percent), who’s thinking about running for the Senate; and Jim Gerlach of Pennsylvania (72 percent), who’s considering a bid for governor. Their occasional departures from the GOP line enabled them to win re-election in 2008 in districts that voted heavily for Obama.

An independent-minded voting record has enabled Republican Dave Reichert , who represents Seattle suburbs, to narrowly win three elections in a district that is trending Democratic. Reichert’s 66 percent party unity score is the fifth-lowest among House Republicans. He’s expected to face a competitive race again in 2010.

Lance (74 percent), one of the eight Republicans who voted for the climate change bill, is one of three Republican freshmen from districts that Obama won in 2008. The others are Cao, the leading House GOP dissenter, and Erik Paulsen of Minnesota, who has a 91 percent unity score that aligns him much more closely with his party peers.

Rachel Bloom contributed to this report.