WASHINGTON -- Liberal advocacy groups are aggressively targeting Democratic state lawmakers who've sided with Republicans to block action on President Barack Obama's health reform law -- with some success.

Two conservative state house Democrats who opposed Obama's health care law lost Democratic primaries in April to more liberal opponents. In Oregon's 48th House District, five-term incumbent Mike Schaufler, who sided with Republicans in voting against the creation of a state health care exchange, an integral part of the Obama reform, is facing a serious challenge from a progressive opponent, Jeff Reardon.

The campaign drives by progressive groups that include MoveOn.org and the Working Families Party are an outgrowth of a two-year effort to support Obama's heath reform. The campaign, which also includes labor unions, reflects the progressive movement's commitment to the law and to defeating those who oppose it.

Reardon, the retired teacher facing Schaufler in Tuesday’s Oregon primary, garnered the support of MoveOn and allied groups in no small part because of Schaufler's vote on health care. The groups have campaigned hard for Reardon, organizing a weekend get-out-the-vote effort to unseat Schaufler.

With Oregon's lower legislative chamber split evenly between Democrats and Republicans -- Schaufler often crossed the aisle to vote with the GOP, particularly on fiscal issues -- the election could have significant implications.

The Oregon League of Conservation Voters sent out a mailer singling out Schaufler's vote against Obama’s health care reform plan and juxtaposing Schaufler's face with Sarah Palin’s. "Mike Schaufler Stands with Tea Party Republicans," it read, according to reporting from The Oregonian.

Meanwhile Pennsylvania Reps. Jason Altmire and Tim Holden, Democrats who opposed the health care law, both lost in primaries to more liberal opponents who attracted the support of activist groups. Altmire's health care opposition, which helped him win reelection in 2010, did not play so well in the redrawn district and Holden's opponent, lawyer Matt Cartwright, made Obama's health care law a central issue in his campaign.

The New York Times's Jonathan Weisman in April wrote that "Democratic voters and party activists see [health care reform] as a major achievement and are poised to punish Democrats who fought it," adding that "health care could be a major rallying cry if the Supreme Court overturns all or part of the law this summer."