President Trump on Monday referred to lawyers working for special counsel Robert S. Mueller III as “thugs” and accused them of trying to affect this year’s elections, further ramping up his rhetoric against prosecutors probing Russian interference in the 2016 U.S. presidential election.

In morning tweets, Trump called Mueller “disgraced and discredited” and said his team of prosecutors is “a National Disgrace!”

The tweets were the latest in a spate of complaints in recent days from the president about a probe into whether his campaign coordinated with Russia during the 2016 election and whether Trump has sought to obstruct the investigation.

In Monday’s outburst, Trump continued to attack a New York Times report over the weekend that White House lawyer Donald McGahn had participated in at least three interviews with Mueller’s team that spanned 30 hours.

“Anybody needing that much time when they know there is no Russian Collusion is just someone looking for trouble,” Trump asserted.

McGahn has offered detailed accounts of “episodes at the heart of the inquiry” over whether Trump and his aides sought to obstruct justice, the Times reported. The paper said McGahn was motivated in part by fear that the president might set him up to be held responsible.

In his tweets, Trump said McGahn had cooperated with prosecutors with his approval “for purposes of transparency.”

Trump’s accusation that the probe could have an impact on the fall elections comes as his lawyers and Mueller’s team continue a lengthy back-and-forth over whether Trump will sit down for an interview with the special counsel’s team. The president’s legal team has sought to take certain topics, such as possible obstruction of justice, off the table.

Trump lawyer Rudolph W. Giuliani recently told the Wall Street Journal that Trump would not sit for an interview after Sept. 1 because it might interfere with the midterm elections in November.

Trump also re-asserted in his Monday tweets that “there was no collusion” between his campaign and the Russians and said efforts to build a case of obstruction were the result of prosecutors being frustrated because they found no coordination.

“If you FIGHT BACK or say anything bad about the Rigged Witch Hunt, they scream Obstruction!” the president wrote.

In tweets over the weekend, Trump compared Mueller’s investigation to the tactics employed by the late senator Joseph McCarthy, who alleged that communist agents and Soviet spies had infiltrated the U.S. government, accusing some of treason without evidence.

Some of Trump’s critics have suggested the president, who last week stripped the security clearance of former CIA director John Brennan and has vowed to pursue similar actions against a list of other critics, is the one who is acting like McCarthy.

David Nakamura contributed to this report.