The House approved legislation Thursday that would tighten the eligibility requirements for participation in health insurance exchanges, Medicaid and other programs under last year's healthcare law, making it harder for middle-income Americans to qualify for these programs.

The House approved the bill, H.R. 2576, on a 262-157 vote in which 26 Democrats voted for the measure.

The Congressional Budget Office has estimated the change could effect eligibility for as many as 1 million people.

House passage, virtually guaranteed by the Republican majority, was made even easier in light of the Obama administration's announcement on Tuesday that it supports the legislation. 

While the White House offered only a terse statement in favor of the bill, its support for the legislation is widely seen as an admission that the healthcare law incorrectly broadened eligibility for Medicaid and other programs.

House passage sends the bill to an uncertain fate in the Senate. Many House-passed bills have not been taken up, but Obama's support for the bill may allow it to surface in the upper chamber.

The bill is seen as the House "pay-for" for another bill, H.R. 674, that would end a 3 percent tax withholding requirement. The House was expected to approve that tax repeal bill by noon Thursday.

The healthcare bill would require Social Security benefits to be included as income when determining modified adjusted gross income (MAGI), which helps determine eligible income levels for health programs. That change would make it harder for middle-income Americans to qualify for these programs, a change many say would help ensure these programs are reserved for lower-income Americans.

During Thursday debate, Republicans argued that the change would also bring the MAGI definition back into line with other federal programs.

"By aligning this definition with other federal subsidy programs, the legislation ensures that taxpayer funds will not be used to enroll middle-class individuals into Medicaid, which is an abuse of the program's mission to provide targeted assistance to those who are most in need of help," Camp said.

While some Democrats supported this change, a few protested. They said that while some see the MAGI calculation as a "glitch" that needs to be corrected, supporters instead see it as a way to broaden healthcare access.

"This provision was not a glitch," said Rep. Joseph Crowley (D-N.Y.), who was the most vocal supporter of the current provision on the floor today. "It was written into the law deliberately, and anyone who would have read the bill would have known that."

Crowley added that Obama's support for the change should be irrelevant, since passing the bill would have the effect of making it harder for hundreds of thousands of Americans to find health coverage. CBO estimates the change would affect between 500,000 and 1 million people.

"I don't care if the president is going to sign this bill," he said. "It doesn't make it right."

Republicans argued that under current law, the MAGI language would not take effect until 2014, and said affected individuals and families would still be able to receive health insurance premium subsidies under the law.