Acknowledging that he had vowed to eliminate the Energy Department when he ran unsuccessfully for the 2012 Republican presidential nomination, the former four-term governor of Texas said those campaign pledges "do not reflect my current thinking."
"In fact, after being briefed on so many of the vital functions of the Department of Energy, I regret recommending its elimination," he added.
That about-face cleared the way for a relatively gentle three-hour interrogation by the
Perry also shifted his views on climate change. As an early candidate in last year's presidential primaries, Perry denied that human activity played a role in causing global warming, a position that appeared to put him in sync with Trump.
On Thursday, Perry told the Senate committee that he accepted the scientific consensus that "man-made activity," specifically the burning of fossil fuels, was at least partly responsible for rising temperatures.
"The question is how we address it in a thoughtful way that doesn't compromise economic growth, the affordability of energy, or American jobs," he said.
Perry denied any responsibility for a questionnaire that the Trump transition team sent to the Energy Department last month requesting the names of employees and contractors who took part in international climate change talks over the last five years, as well as on Obama administration efforts to lower the nation's carbon output.
The request for names sparked concerns that the incoming administration would seek to purge climate change scientists and other civil servants, and the department announced it would not provide any names.
"The questionnaire went out before I was selected," Perry said. "I don't approve it. I don't need that information. I don't want that information."
"I am going to protect all of the science," he later added.
Perry is an unyielding backer of opening up more land for oil drilling and hydraulic fracturing, or fracking. Although he backed the increased use of wind turbines and other alternative power sources in Texas, he has supported ending government subsidies for renewable energy.
Perry vowed to boost cybersecurity to defend the nation's electrical grid and other networks from what he called "cybersnooping." Hackers have targeted individual utilities, and experts warn that parts of the national grid may be vulnerable to a sustained digital assault.
Perry also pledged to ensure security for the country's aging nuclear weapons stockpile and modernization efforts that are underway. He said he had asked Lt. Gen. Frank G. Klotz, head of the National Nuclear Security Administration, to stay in place to assure "continuity."
If confirmed by the Senate, Perry's support could prove crucial to the four national laboratories in California that depend on Energy Department funding.
Perry, 66, has no scientific background, a sharp change from outgoing Secretary
Moniz was deeply involved in negotiating the international accord to prevent Iran from building a nuclear weapon. As a candidate, Perry called for the deal to be scrapped, but on Thursday, he said he hadn't been briefed on it.
"I think all of us can say we want them to live up to the deal," he said.
Outside of Texas, Perry is perhaps best known for seeking to abolish the department Trump has picked him to lead.
During a televised candidate's debate in the 2012 primary race, Perry pledged to eliminate three federal departments that he said were unnecessary.
But he forgot the name of the Energy Department, a gaffe that's been called the "oops" moment that helped sink his campaign.
"It's three agencies of government, when I get there, that are gone: Commerce, Education and, the, uh, what's the third one there?" Perry said. "Commerce, Education and the, uh, the, uh…."
He continued, "The third agency of government I would do away with — the Education, uh, the, uh, Commerce, and let's see — I can't ... the third one, I can't. I'm sorry. ... Oops."
11:05 a.m.: This article was updated with details from Thursday's hearing.