President Donald Trump wanted to order the Justice Department to prosecute former Secretary of State Hillary Clinton and former FBI Director James Comey in spring 2018, according to the New York Times.

But Trump was ultimately dissuaded after White House Counsel Donald McGahn wrote a memo that said Trump risked impeachment as well as defeat in the 2020 presidential election if voters through he had abused his power.

Justice Department lawyers could also refuse to act on Trump’s orders, the memo reportedly said. Under Richard Nixon, several officials refused to honor presidential orders, starting with special prosecutor Archibald Cox, who was fired by Nixon. That firing precipitated Nixon’s resignation.

In Trump’s case, Justice Department refusals could set off a legal crisis. A judge could also dismiss any charges the president ordered against Comey and Clinton.

Despite that, the report says that Trump continues to discuss the possibility of a legal attack, including an appointment of a special counsel to investigate Clinton and Comey. Trump has said that Clinton violated the law over the use of a private email server during her time as secretary of state, and alleged that Comey shared information with the New York Times in violation of federal law.

On the campaign trail and in campaign-style rallies since his election, Trump has led the call against his former presidential opponent to “lock her up.” But this Times report marks the most explicit account yet of his attempts to use the government to settle scores. Previously, Trump’s closest action was to revoke security clearances for several administration critics.

McGahn reportedly told Trump that the president had no authority to order a prosecution, and that even formally demanding an investigation—rather than Trump’s off-the-cuff remarks and tweets about the matter—could lead to accusations of abuse of power.

McGahn had White House lawyers draft a memo explaining potential consequences of Trump ordering a prosecution, which included the potential of impeachment charges, according to the Times. It’s unclear if Trump read McGahn’s briefing.

The White House declined comment to the Times about the latest report, as did McGahn, who left his position a month ago.

Neither Clinton nor Comey have been charged with crimes related to their tenure in office or the presidential election, although Clinton was investigated by the FBI over her private server. No charges resulted.

No current investigations are known to be underway, although then-Attorney General Jeff Sessions said in November 2017 that the Justice Department was looking into whether to investigate an Obama-era decision in which Russia received clearance to buy a uranium mining company. Trump claimed that the Clinton Foundation was involved in the decision, led to that conclusion by Fox News and right-wing media outlets.