WASHINGTON — President Trump’s plans to combat the nation’s opioid epidemic were disrupted on Monday as he came under pressure to abandon a nominee for drug czar who championed legislation undercutting the government’s power to go after pharmaceutical companies that contribute to the crisis.

Even as the president promised to announce a major initiative to stem the wave of opioid abuse as early as next week, Mr. Trump said he would consider scuttling the nomination of Representative Tom Marino as director of the Office of National Drug Control Policy. Mr. Marino, Republican of Pennsylvania, pushed the legislation sought by lobbyists for the drug industry.

“He’s a good man,” Mr. Trump said during a news conference on Monday in the Rose Garden. “I have not spoken to him, but I will speak to him, and I’ll make that determination. And if I think it’s 1 percent negative to doing what we want to do, I will make a change, yes.”

The president also suggested that he might favor rethinking the law that Mr. Marino helped pass. “We’re going to look at that very closely,” he said.