President Trump on Thursday indicated he may attempt to block former White House counsel Don McGahn from testifying to Congress, a move that would escalate his war against Democrat-led investigations.

Trump said he does not "think [he] can let" McGahn speak to congressional investigators and then try to stop other White House aides from cooperating with House Democrats' probes into his administration, campaign and businesses.

"I can't say, 'Well one can and the others can't,'" Trump said during an interview with Fox News. "I would say it's done. We've gone through this."

Trump's comments provide one of the clearest indications yet the White House will fight House Democrats' subpoena for McGahn to appear before the Judiciary Committee, which is looking for more information about special counsel Robert Mueller's Russia investigation.

Some Democrats have urged party leaders to use the Judiciary investigation as a starting point for impeachment proceedings.

The president said he does not plan to cooperate with congressional investigations after allowing many aides to speak to Mueller's team and providing his investigators with thousands of documents.

"Nobody has ever done what I've done. I've given total transparency," Trump said. "They shouldn't be looking anymore. This is all - it's done."

Trump has previously said he plans to fight "all the subpoenas" issued by the House, but has not commented specifically on McGahn's case.

The White House has already telegraphed it may invoke executive privilege to block McGahn and other presidential advisers from answering questions from Congress about matters related to the Mueller probe.

In a letter that became public on Thursday, White House lawyer Emmet Flood argued that Trump's decision not to make a privilege claim over the special counsel report does not prevent him from invoking privilege to prevent advisers' congressional testimony.

Some outside legal experts disagree with Flood's argument.

McGahn was a key witness for Mueller; he appeared in the special counsel's report roughly 150 times while providing damaging information about Trump's attempts to fire Mueller, among other episodes that were investigated for obstruction of justice.

Trump was not charged with any crimes as a result of the probe.

Brett Samuels contributed.