Republicans and outside groups have seized on problems with the law to pummel Democrats who voted for "Obamacare," as the GOP looks to increase its majority in the House and grab control of the Senate. In Oregon, first-term Sen. Jeff Merkley has defended the law at town halls and is certain to face more challenges on the issue. He has said he is working on legislation to fix the law.
His likely Republican opponent is Monica Wehby, a pediatric neurosurgeon who has been critical of "Obamacare."
In the next eight months before the election, Republicans who call the shots in the House will cast a harsh spotlight on the law through hearings and narrowly focused legislation designed to divide Democrats. The GOP has done it this year with bills requiring the Obama administration to report weekly on how many Americans have signed up for health care coverage and a measure bolting new security requirements on the law.
One bill drew the support of 33 Democrats; the other attracted 67 Democrats who bucked the administration.
Last year, House Republicans voted more than 40 times to repeal, replace or gut the law, and strong GOP opposition to "Obamacare" precipitated the 16-day partial government shutdown last fall that was a political blow to Republicans.
Since recovered, Republicans say privately they are unlikely to push for full repeal in light of the law's popular elements, such as insurance for individuals even with an existing condition and allowing children to remain on their parents' plans until age 26. Also, Republicans have been unable to unify around an alternative to health care plan.