BATON ROUGE, La. — President-elect Donald J. Trump promised on Friday that his administration would strip away “job-killing restrictions” on energy production and encourage the construction of refineries in the United States, as he campaigned for Republican candidates in a state heavily dependent on the oil and gas industry.

“We will cancel the job-killing restrictions on the production of American energy,” Mr. Trump said in an airplane hangar in Baton Rouge, the day before Louisiana voters go to the polls to vote for Senate and House candidates. “We haven’t had refineries built in decades, right? We’re going to have refineries built again.”

His comments came a day after he had announced his selection of Scott Pruitt, Oklahoma’s attorney general, as administrator of the Environmental Protection Agency. Mr. Pruitt is a staunch ally of the energy industry who has teamed up with companies to undercut the Obama administration’s climate regulations.

Mr. Trump pledged to enact a “massive” tax cut for the middle class, roll back Obama-era regulations, pass a $1 trillion infrastructure program and build a wall on the southern border to prioritize American people and jobs.