Rep. Tom Marino of Pennsylvania AP Sen. Joe Manchin of West Virginia sent President Donald Trump a letter on Monday asking him to withdraw his nomination for a top drug policy position. And now Senate Minority Leader Chuck Schumer is joining the chorus of voices calling on Trump to reconsider.

The request came a day after a joint investigation from the Washington Post and CBS' "60 Minutes," which concluded that Congress and the drug industry fueled the opioid crisis.

One of the most instrumental people, the investigation found, was Rep. Tom Marino of Pennsylvania, a Republican whom Trump nominated to lead the White House Office of National Drug Control Policy, a position commonly referred to as the nation's "drug czar."

Specifically, Marino introduced a bill in 2014 that made it harder for the Drug Enforcement Administration to enforce laws that would keep opioids from being diverted to people who might abuse them. A version of the bill became law in 2016.

The Post called it "the crowning achievement of a multifaceted campaign by the drug industry to weaken aggressive DEA enforcement efforts against drug distribution companies that were supplying corrupt doctors and pharmacists who peddled narcotics to the black market."

Manchin said the Post's report led him to question Marino's ability to act as drug czar.

"Congressman Marino no longer has my trust or that of the public that he will aggressively pursue the fight against opioid abuse," Manchin said in the letter.

—Senator Joe Manchin (@Sen_JoeManchin) October 16, 2017

During a news conference on Monday afternoon, Trump said he would look into Marino, whom he called a "great guy."

"We're going to look into the report and we're going to take it very seriously," Trump said, with Senate Majority Leader Mitch McConnell by his side, adding "We're going to be looking into Tom."

Manchin and Schumer weren't the only senators to take action based on the investigation. Sen. Claire McCaskill of Missouri also introduced a bill on Monday aiming to repeal the 2016 law.

"Media reports indicate that this law has significantly affected the government's ability to crack down on opioid distributors that are failing to meet their obligations and endangering our communities," the top-ranking Democrat on the Homeland Security and Governmental Affairs Committee said in a news release.