President-elect Donald Trump has promised a sharp, dramatic about-face on the Biden administration’s energy policies — including “drill, baby, drill” and a sharp drop in Americans’ fuel prices.

Meeting some of those pledges won’t be easy. Or quick. Federal bureaucracy grinds slowly, and the energy markets don’t move at presidents’ whims.

These are among the energy promises Trump pledged for Day 1 — and his odds of delivering on them:

Cutting energy bills in half — in a year: “If you make doughnuts, if you make cars — whatever you make, energy is a big deal, and we’re going to get that — it’s my ambition to get your energy bill within 12 months down 50 percent,” Trump promised at a rally in September.

That’s essentially an impossible goal, energy experts say.

Oil prices move on a global market, and a president can do little to significantly change them. The U.S. is already producing oil at peak levels. And while Trump is certain to remove regulations and ease permitting on fuel production, that won’t dramatically cut prices, and producers certainly don’t want to see prices bottom out.

“It’s going to be a struggle for him to be able to bend the system enough to be anywhere in the ballpark of cutting energy prices in half,” said Patrick De Haan, head of petroleum analysis at GasBuddy.com. “I would call it virtually impossible, short of an economic collapse, or short of something else that’s difficult to imagine at this point.”

Axing all price-raising regulations: “On Day 1, I will sign an executive order directing every federal agency to immediately remove every single burdensome regulation driving up the cost of goods,” Trump said while campaigning in Albuquerque, New Mexico.

But rescinding regulations finished by a previous administration takes time.

A new administration must make a robust case for why it’s pulling back, issue a proposal, take public comment and respond to those comments. For complex rulemakings, the process typically takes two or three years.

And opponents can sue. Almost 80 percent of the first Trump administration’s regulatory actions were defeated in court, the Institute for Policy Integrity at New York University School of Law estimated.

Tying disaster aid to bending to Trump’s will: Trump made this threat explicit during a rally in California rally, saying he would force Democratic Gov. Gavin Newsom to increase water deliveries to agriculture if he wanted disaster relief money.

“We’ll force it down his throat, and we’ll say, ‘Gavin, if you don’t do it, we’re not giving you any of that fire money that we send you all the time for all the forest fires that you have,’” Trump vowed.

This threat is legitimate. Federal law gives the president sole authority to approve or deny a governor’s request to declare their state a “major disaster” and reimburse states for millions — or billions — in recovery costs.

Read this story from POLITICO’s E&E News for more of a reality check on Trump’s Day 1 energy pledges.