Oregon has received $305 million in federal grants to build its exchange, according to the Congressional Research Service.

Representative Greg Walden, Republican of Oregon, said: “Cover Oregon is the worst financial failure in information technology in state history, and it was completely avoidable. Today’s admission of failure underscores the need to stop the waste and get the truth. How did this happen? Who was in charge?”

Representative Darrell Issa, Republican of California and chairman of the House Committee on Oversight and Government Reform, was equally critical. “Federal officials should insist that Oregon foot the bill for the state’s transition to the federal exchange,” he said. “Federal taxpayers should not be stuck with the bill twice for this disastrous project.”

Kathleen Sebelius, the secretary of health and human services, approved the Oregon exchange on Dec. 7, 2012, saying she was confident that it would be ready to provide coverage to consumers in 2014. But in February, the federal government delivered a devastating critique of the Oregon exchange, saying it had “no integrated project schedule” and no “overarching dedicated project manager” to keep work on track. Moreover, it said, the state did far too little to supervise its main information technology contractor, Oracle.

For Mr. Kitzhaber, a former emergency room doctor who has staked his political career on health care issues, and for Democrats in the Oregon Legislature who backed his enthusiastic embrace of the Affordable Care Act, the political fallout is far from over. He is running this fall for a fourth term and has said he expects the exchange’s failure to be the issue of the campaign. But he has a fund-raising advantage over Republican rivals, and it will be an uphill battle for Republicans to unseat him in a Democratic-leaning state that has not elected a Republican governor since 1982.

In any case, health policy debates in Oregon, which once seemed a matter of shared consensus, have become deeply politicized, and the issue is likely to reverberate in state politics between now and Election Day.

Oregon is not the only state to shift course. Maryland decided three weeks ago to abandon its dysfunctional website and use software developed for the Connecticut exchange, one of the most successful in the country.