WASHINGTON —Sen. David Vitter led a rare Republican boycott Thursday to successfully delay committee approval of the nominated Environmental Protection Agency administrator.

Vitter, of Louisiana and the ranking member of the Senate Environment and Public Works Committee, along with seven Republican colleagues on the panel, skipped the vote for President Barack Obama’s nomination to lead the EPA, Gina McCarthy. Vitter’s boycott left the committee one vote shy of being able to move her nomination forward.

Vitter and other Republicans argued that the EPA lacks “openness and transparency,” in terms of its research and communications. The agency refuses to release all of the scientific justifications for its “clean” air and water regulations on businesses and industries, Vitter said in a news conference separate from the committee hearing.

“Pretty ironic that we’re not getting this out of the EPA — sunshine,” Vitter said.

Committee Chairwoman Barbara Boxer, D-Calif., and other Democrats articulated a different view. They argued Republicans intentionally submitted more than 1,000 questions for McCarthy to answer — far more than any previous nominee — half of them coming from Vitter.

McCarthy heads the EPA’s air and radiation office. And throughout her career, McCarthy has worked for multiple Republican governors.

“(McCarthy) is perhaps the most-qualified nominee to ever head the Environmental Protection Agency,” Boxer said. “I have never seen in my life a nominee answer more questions than Gina McCarthy.”

Vitter said the issue is not about the 1,000 questions, but about a few core issues regarding transparency, including alleged secretive internal email systems — and not disclosing scientific studies.

Vitter pointed to an executive order Obama issued Thursday morning that makes it easier to publicly release data generated and stored by the federal government as evidence that the president also wants more transparency.

A frustrated Boxer said she left a glass of water for Vitter, in case he decided to change his mind and join the hearing.

“At this point, their (GOP) opposition, even in allowing us to vote, it shows how outside the mainstream they are; how obstructionist they are,” Boxer said. “We just had an election … This is not Mitt Romney’s Cabinet. This is not (Texas Gov.) Rick Perry’s Cabinet.”

“We’re not asking or expecting the president’s administration to change their bedrock views,” Vitter later responded.

Democrats fell one vote shy of approving McCarthy on their own because of the absence of Sen. Frank Lautenberg, D-N.J., who has only made rare appearances to Washington, D.C., this year because he is mostly wheelchair bound while recovering from a serious bout with the flu and bronchitis.

Boxer said they will work with Lautenberg and reschedule when he is able to attend. Otherwise, she encouraged Vitter to step in out of respect for Lautenberg’s health issues.

Once McCarthy is approved by the committee, she will face the difficult task of receiving the needed 60 Senate votes, rather than a simple majority, for full confirmation, because of a Republican procedural block.

“President Obama’s EPA is actually making it harder for Americans to get to work,” said Sen. John Barrasso, R-Wyo., before Vitter shifted the discussion back to “transparency.”

Sen. Sheldon Whitehouse, D-R.I., said the boycott seemed more like Republicans being upset that McCarthy is not a pawn of the oil and coal industries. “It looks like they’re really just trying to throw more sand in the gears rather than get their questions answered,” Whitehouse said.

Sen. Mark Udall, D-Colo., also complained about what he called the every-growing GOP obstructionism to block legislation and confirmations. “It’s a sad day when we have an entire party won’t show up to do their work,” Udall said. “It’s an outright abuse of our rules.”

Vitter said Thursday’s boycott was not unprecedented. In 2003, Democrats boycotted the EPA vote for President George W. Bush’s nominee, Michael Leavitt, although the Democrats relented two weeks later.