A Democratic-controlled Senate committee backed President Barack Obama's choice to lead the Environmental Protection Agency on Thursday, sending the nomination to the full Senate for a confirmation vote.
The 10-8 vote along party lines for Gina McCarthy, currently the agency's top air-quality official, came a week after Republicans in the Senate Environment and Public Works Committee boycotted a planned vote.
No date has been set for a floor vote on McCarthy, said California Democrat Barbara Boxer, the committee chairwoman.
David Vitter of Louisiana, the ranking Republican, said the decision to attend the vote came after "meaningful progress" in talks with acting EPA Administrator Bob Perciasepe on five key requests for explanations about the agency's operations.
The earlier boycott was the latest in a series of procedural moves by Republicans that have made it difficult for Obama to get his second-term Cabinet in place.
The logjam broke up somewhat on Thursday with advancement of McCarthy and that of Thomas Perez, nominee for secretary of labor, which also came after a party-line vote in committee.
The full Senate is expected to vote later on Thursday on whether to confirm nuclear physicist Ernest Moniz as U.S. Energy Secretary. Unlike McCarthy and Perez, Moniz breezed through a committee vote in April.
McCarthy is likely to face a tough vote when her nomination comes to the full Senate.
Republican Roy Blunt of Missouri maintains a hold on McCarthy's nomination in a dispute about a repairing a levee system on the Mississippi River.
If the hold is not lifted, McCarthy will need 60 votes in the 100-member chamber to win confirmation. The Democrats hold 53 Senate seats against 45 for the Republicans. Two independent senators typically side with the Democrats in votes.
In recent weeks, Republican senators have posed more than 1,000 written questions to McCarthy, a tally that Democrats say is a new record. An administration official said last week she had answered every one.
Vitter said he wants to see additional responses from Persiasepe about his concerns over the agency's economic modeling of its proposed rules, among other things.
Boxer told reporters she was skeptical of the Republicans' tactics: "Everything I have seen tells me they want to get a certain answer. Don't let her (McCarthy) twist in the wind with the threat of filibuster," she said.