A House committee approved legislation Wednesday opening federal benefits to same-sex domestic partners of federal employees.

The House Oversight and Government Reform Committee voted along party lines on HR 2517 after hours of heated debate over whether the bill redefines marriage.

Republicans said the government cannot afford to take on an estimated 30,000 new enrollees at a cost of $56 million in 2010. Expanding federal benefits is inappropriate when unemployment is 10.2 percent, said Republican ranking member Darrell Issa of California.

"We're taking up a bill that casts aside all concerns about fiscal responsibility in order to bestow a costly benefit on a select group of federal employees," he said, adding that the administration hasn't provided the committee with an estimate of how adding more enrollees could affect premiums.

The bill is sponsored by Rep. Tammy Baldwin, D-Ill., who is gay.

The House likely has enough votes to ensure the bill's passage, though approval in the Senate is unlikely, as just one senator can block a bill. Republicans in the Senate are expected to oppose the measure.