A year after he entered the White House with a vow that fighting global warming would be a driving priority for his administration, President Biden finds his climate agenda is mired in delay and faces legal, legislative and political headwinds that could diminish or dismantle it entirely.

His two main avenues for significant climate action are legislation and regulation. But even Mr. Biden’s top aides and closest allies now concede that the legislative centerpiece of his climate plan is unlikely to become law in the face of steadfast Republican opposition. And regulations that are now under development — strict limits on the pollution from cars and power plants that is dangerously heating the planet — could be curtailed or blocked by the conservative majority on the Supreme Court.

With gasoline prices surging after the Russian invasion of Ukraine and images receding of last summer’s climate disasters — wildfires that raged through seven states, heat waves and floods — Republicans and oil companies are newly emboldened in calling for more drilling and less emphasis on climate change.

“The U.S. oil companies are like a prisoner that was condemned to death, and suddenly the warden of the prison lets them out and wants them to produce as much oil as quickly as possible,” said Robert McNally, a consultant who was a senior energy and economic adviser to President George W. Bush. “Now, the president is saying to them, help me out of a jam. It’s a panicked response to high oil prices.”

On Thursday, President Biden said he would release one million barrels of oil a day from the Strategic Petroleum Reserve for as long as 180 days to help bring down global oil prices. The scale and duration of such a release would be historic. The United States also plans to increase exports of natural gas to help Europe wean itself from Russian supplies. Environmentalists are concerned that both of those moves will lead to more domestic drilling at a moment when scientists say nations must sharply and quickly cut fossil fuel use.