No one has been charged over the investigation of Abbe Lowell, the lawyer, and Elliott Broidy, a prominent fund-raiser for Trump, who were involved in the effort, the paper said, citing two people familiar with the investigation.
In a statement, Broidy's lawyer, William Burck, said his client was "not under investigation and has not been accused by anyone of any wrongdoing whatsoever."
Reuters could not immediately reach representatives of Lowell and the Justice Department to seek comment.
The alleged scheme was aimed at securing clemency for a Berkeley, California-based psychologist, Hugh Baras, who was convicted in 2014 of tax evasion and improperly claiming Social Security benefits, the paper said.
As part of the plan, a San Francisco real estate developer, Sanford Diller, would make an unspecified political contribution, it added. Diller died in 2018.
Burck said Broidy's only role was putting Diller in contact with Lowell.
Baras, who jailed for more than two years, did not receive clemency from the White House. He was released from prison in August 2019, according to the Federal Bureau of Prisons.
The newspaper fleshed out details of the investigation, first revealed on Tuesday in heavily-redacted court papers that did not disclose details of the alleged crime or the identities of those involved.
At the time, Trump described the investigation as "Fake News!" on Twitter.
US District Judge Beryl Howell released an order that described what she called a "bribery-for-pardon" investigation.
Federal prosecutors in Washington said they had obtained evidence of a bribery scheme for someone to "offer a substantial political contribution in exchange for a presidential pardon or reprieve of sentence," the documents showed.
In October, Broidy pleaded guilty in a separate case to legally lobbying Trump to drop an investigation into a Malaysian embezzlement.