Republicans have said they do not believe that many of the Medicare cuts will ever take hold. They say that government subsidies to help people buy health insurance will prove far costlier than the budget office has predicted, and that the Democrats wrote the law to mask the steep future costs of some provisions, like a new long-term-care insurance program.

The budget office did not comment on Mr. Boehner’s remarks. Douglas W. Elmendorf, its director, has frequently said his office applies the longstanding budget rules. He says it uses its own professional expertise, as well as consulting with outside experts, to derive its projections, which represent the “middle of the distribution of likely outcomes.”

Mr. Elmendorf has warned that Congress may find it difficult to follow through with parts of the health care law, particularly the cuts to Medicare. The law’s cost would rise if the cuts were not enacted.

In the report on Thursday, Mr. Elmendorf, a former Clinton administration official appointed in 2008 when Democrats controlled both chambers of Congress, said that a preliminary analysis showed that repealing the law would increase federal budget deficits by a total of $145 billion from 2012 to 2019 and by $230 billion between 2012 and 2021.

Moreover, he said, if the law is repealed, 32 million fewer people will have health insurance in 2019, compared with estimates of coverage under the existing law. As a result, he said, the number of uninsured would be 54 million, rather than 23 million, in 2019.

At Mr. Boehner’s news conference, reporters peppered him with questions about repealing the law — including the cost analysis and a plan by Republicans not to allow amendments on the repeal measure even though the party had promised to maintain a more open legislative process.