Former Massachusetts Gov. Mitt Romney has pledged to dismantle the law if he defeats Obama. And stripping funding for its main parts would be relatively easy for a GOP Congress, even if the party had only a narrow majority in the Senate.

Even if Obama wins a second term, there is no guarantee the law will survive in its current form. Pressure is mounting in Washington to dramatically cut federal spending as budget deficits yawn. And the president and other supporters of the law may be hard-pressed to defend the $1.7-trillion price tag for expanding insurance coverage over the next decade. …

Republicans on Capitol Hill, who plan another symbolic vote in July to scrap the law, are promising to go after the law’s funding next year, a pledge that will be hard to walk away from. “The real outcome of … [the court’s] decision is to strengthen our resolve to make sure that this law is in fact repealed,” House SpeakerJohn A. Boehner(R-Ohio) said.