Climate change dominated the conversation at a nomination hearing Thursday for an inconspicuous but controversial position in the U.S. Environmental Protection Agency.

The assistant administrator for the EPA's Office of Air and Radiation doesn't make headlines very often, but in the past decade or so, policymakers are increasingly scrutinizing nominees for the office because they can have a major impact on far-reaching climate-change policies.

That led to partisan squabbling over the previous administration's nominees for the position, with Democrats blocking approval.

Now, the tables have turned, putting Republicans in the minority. Sen. James Inhofe, R-Okla., hinted his side of the aisle would employ similar tactics in the approval of President Barack Obama's pick for the job, Regina McCarthy, current commissioner of Connecticut's Department of Environmental Protection.

"The Senate has not confirmed a nominee for this position in eight years -- due entirely to opposition from my colleagues on the other side of the aisle," Inhofe, ranking member of the Committee on Environment and Public Works, said at McCarthy's nomination hearing. "Opposition arose from allegations that nominees failed to provide timely and complete answers to questions submitted to them. In effect, Madam Chairman (Barbara Boxer, D-Calif.), a standard was set by you and your colleagues: In order to advance this nomination as expeditiously as possible, the minority will need timely and complete answers to our questions."

Those questions relate to how McCarthy will handle controversial climate policies.

This is "one of the toughest jobs in the EPA," said Sen. George Voinovich, R-Ohio. "Ms. McCarthy will be responsible for administering some of the most complex and contentious regulatory issues facing the Obama administration."

These issues include a longstanding struggle between California and the EPA that began under the Bush administration. In 2005 California requested that the agency grant it a waiver, allowing the state to impose stricter pollution standards for motor vehicles than current federal regulations, but the EPA denied the state's request.

Soon after Obama's new EPA leader, Lisa Jackson, stepped into office, though, the agency decided to reconsider California's request. That has Democrats cheering and hopeful that McCarthy will push for moves toward stricter pollution controls.

"This nomination is especially important to the people of my state," said Boxer, chair of the EPW Committee. "The California Air Resources Board estimates that diesel emissions contribute to approximately 2,000 premature deaths each year and that the health costs of diesel emissions are billions of dollars each year."

Perhaps the most controversial issue that will fall on McCarthy's desk if she's nominated, though, is EPA's decision on whether and how to regulate greenhouse gasses under the Clean Air Act.

This possibility is particularly troubling to Republican policymakers, who largely oppose federal limitations on carbon emissions.

"CAA regulation would set forth a multitude of costly, burdensome programs regulating nearly every aspect of American's lives," Voinovich said. "The Act was not designed to address a global environmental phenomenon like climate change in an efficient and effective manner."

Democrats, though, encouraged McCarthy to do everything in her power to use the act as a means for decreasing domestic emissions.

"Make sure you do what you can under the law," said Sen. Tom Udall, D-N.M. "It's not clear at all to me that Congress is going to act."

From McCarthy's answers, it looks like Democrats might get what they want.

"It's very clear Obama wants a cap-and-trade program (to regulate) greenhouse gasses at the federal level," McCarthy said. "I'll support that in any way I can."

Her record on the issue is impressive. She played a key role in creating the Regional Greenhouse Gas Initiative, the nation's first mandatory cap-and-trade program -- a system that caps emissions at a certain level and requires entities covered by the program, usually large emitters such as power plants, to own shares for the pollution they produce. So far, 10 Northeastern states have signed up to participate in the program spearheaded by McCarthy.

Congressional Democrats are pushing for a similar program on the national level, which makes McCarthy's experience a definite plus, said Sen. Chris Dodd, D-Conn.

"The Commissioner's work on the issue of climate change has been recognized and lauded nationally, and her experience will be invaluable when she is confirmed as assistant administrator for air and radiation," Dodd said.

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