President Trump urged Attorney General Jeff Sessions to reverse his recusal from the federal Russia investigation last year, a new report says.

The conversation allegedly occurred last March at Trump’s Mar-a-Lago estate, where Trump lambasted Sessions for recusing himself from the probe and requested he reverse the decision, the New York Times reports. According to the Times, Session is a key witness in the Russia investigation.

Meanwhile, Sessions pushed back and did not give in to Trump’s request. Deputy Attorney General Rod Rosenstein would go on to appoint special counsel Robert Mueller to spearhead the Russia probe.

Trump and Sessions’ meeting has attracted interest from Mueller, who the Times claims is specifically investigating the incident. Mueller is also looking into the public and private attacks Trump has thrown at Sessions in an attempt to persuade him to resign.

The Justice Department declined to provide comment, and Trump attorney Rudy Giuliani claimed he has not talked to Trump about the recusal.

Mueller is investigating Russian meddling in the 2016 election and whether the Trump campaign colluded with the Kremlin. Additionally, it was reported Mueller expanded his investigation to look at possible obstruction of justice after former FBI Director James Comey’s ouster.