Four days before Brett M. Kavanaugh was confirmed to the Supreme Court by the narrowest of margins, Sen. Christopher A. Coons (D-Del.) sent a letter to the FBI, urging “appropriate follow up” on new information he believed was relevant to sexual misconduct allegations made against the nominee.

Then, apparently, not much happened.

Not at the FBI, which assured Coons it had received the letter but did not interview the person whom the senator referred to the bureau. Not in the office of then-Senate Judiciary Committee Chairman Charles E. Grassley (R-Iowa), which was copied on the letter that contained few in the way of specifics. And not among Democrats, several of whom had been unaware of the information until a New York Times report this weekend detailed a new alleged incident involving Kavanaugh.

That inaction — made public in recent days through new reports about Kavanaugh’s alleged misbehavior — has renewed a bitter debate about how his confirmation was handled, angering Democrats about a process they felt was rushed and animating Republicans who decried what they viewed as attempts to assassinate Kavanaugh’s character. 

The revelations about the process also revived one of the most rancorous episodes in recent political history and thrust it into the center of the 2020 presidential race, as several Democratic candidates called on the Supreme Court’s newest justice to be impeached by the House. 

In an interview Monday, Coons said he was “disappointed and upset” that the scope of the FBI background check — greenlighted by the White House just over a week before Kavanaugh was confirmed at the insistence of Republican senators — was, in his view, “so constrained.” 

“Of many things that are still not known about the whole matter, one of the things that deserves to be better understood is, at whose direction [did] the FBI narrow that investigation?” Coons said. “I don’t think the FBI makes decisions like that on their own about the scope of an investigation. So I think the important question is, at whose direction and what does this say about future nominations?”

One person with knowledge of the process said this week that the White House decided what to investigate based on conversations with senators and what they wanted to know. Republican senators — all of whom supported Kavanaugh except for Sen. Lisa Murkowski (Alaska) — were largely satisfied with the probe. 

The new allegation against Kavanaugh was made public Saturday night in a book excerpt published by the Times from two of its reporters. The report said Max Stier, a Yale University classmate of Kavanaugh who now leads a prominent nonpartisan group in Washington, said he saw Kavanaugh with his pants down at a party, where friends pushed Kavanaugh’s penis into a young woman’s hand.

According to the book, “The Education of Brett Kavanaugh: An Investigation,” the woman involved in the alleged incident has told friends she does not recall it — context that was not included in the first version of the excerpt published on the Times website. 

Coons, an acquaintance of Stier’s who sits on the Senate Judiciary Committee, said in an interview with The Washington Post Monday that Stier had quietly reached out in late September of last year with information he wanted to relay about Kavanaugh to federal investigators. 

He was “very concerned about confidentiality,” Coons recalled. In his initial conversation, Stier seemed optimistic he would ultimately be able to relay his information to the FBI by “reaching out through other means,” Coons said.

But on the night of Oct. 1, 2018, Coons and Stier spoke again, with Stier stressing that the week-long FBI investigation was almost over and imploring Coons for his help. 

“I said, ‘I’m happy to try one more time,’ ” Coons said.

Coons then wrote to FBI Director Christopher A. Wray on Oct. 2, 2018, requesting an “appropriate follow up” with Stier. Although the name was redacted in the one-page letter obtained by The Post, a spokesman for Coons confirmed Monday that the individual was Stier. 

Stier was one of several people who went to Yale at the same time as Kavanaugh who reached out to the FBI last year seeking to provide information, but were not interviewed, according to people familiar with the matter. 

In his letter, Coons said “several individuals” had contacted his office saying they wanted to share information with federal authorities but had “difficulty reaching anyone who will collect their information.”

“I cannot speak to the relevance or veracity of the information that many of these individuals seek to provide, and I have encouraged them to use the FBI tip portal or contact a regional FBI field office,” Coons wrote to Wray. But Stier, Coons added, “was one individual whom I would like to specifically refer to you for appropriate follow up.”

The two top senators on the Judiciary Committee at the time — Grassley and ranking Democrat Dianne Feinstein (Calif.) — were copied on Coons’s letter to the FBI. But neither had information beyond what Coons wrote, according to two Senate aides. The letter does not describe the information Stier said he had in detail.

Stier also did not contact committee leadership, according to officials involved in the process. 

Grassley, who had a team of nearly 40 attorneys and other officials who vetted several Kavanaugh-related accusations last fall, said he found out about the new alleged incident Sunday, after the Times published its report. 

“They did everything we asked them to,” Grassley said Monday of the FBI. “The problem is, there was just a name given. . . . So I think it’s just a case of somebody saying you ought to talk to somebody. That doesn’t give you much to go on.” 

Feinstein told reporters that she “had no other information at that time.” 

“The problem was that the FBI did not do the investigations that we hoped they would do,” Feinstein said. “We need to clear this up.”

Wray has defended the FBI’s handling of the Kavanaugh background investigation, although the House Judiciary Committee, led by Democrats, has indicated the FBI director will face questions on the issue in October, which is the next time he is scheduled to appear before them. 

The FBI’s investigation into the Kavanaugh allegations was always limited in scope, in part because a background investigation is not like a criminal probe to uncover possible wrongdoing. Rather, it is an inquiry made on behalf of a specific client — the White House.

The inquiry into sexual assault allegations made against Kavanaugh was even more restricted because it was a supplemental investigation to the previous FBI background probe.

To address questions raised by Republican senators who were wavering on voting for him, the White House tasked the FBI to do some limited, additional digging, according to people familiar with the matter. Democrats cried foul at the time, saying the FBI was hamstrung by the White House, and the FBI ultimately interviewed fewer than a dozen people connected to two allegations leveled against Kavanaugh.

One was the accusation brought by Christine Blasey Ford, who accused Kavanaugh of sexually assaulting her when both were teenagers in suburban Washington. The other was brought by Deborah Ramirez, another Yale classmate who alleged that Kavanaugh exposed himself during a dorm party. Kavanaugh has denied all the allegations.

“When I heard from several senators that they were being assured that this would be a by-the-book investigation, I called White House counsel [Donald] McGahn and said, ‘Where’s the book? What’s the rules? What’s the background?’” Coons recalled. 

Aides said Coons wrote the Oct. 2 letter because he wanted to get relevant information about credible allegations as quickly as possible to the FBI. Kavanaugh was confirmed Oct. 6. 

As the FBI was wrapping up its investigation, intermediaries working on behalf of Stier delivered his account to agency officials. The intermediaries told The Post last year they had relayed that a classmate of Kavanaugh’s had witnessed an incident while taking a study break at Yale’s Lawrance Hall, a dorm. They declined to give the classmate’s name to The Post.

Devlin Barrett, Josh Dawsey and Mike DeBonis contributed to this report.