US President Donald Trump said on Wednesday that he would participate in a going impeachment enquiry against him led by the House Democrats “if the rules are fair”.

On being asked that if he would participate in the proceedings if the House voted and followed the same rules as to when Congress has previously charged sitting presidents with wrongdoing, President Trump said, “Yes, if the rules are fair”.

“If Republicans get a fair shake,” Trump added.

Trump’s remarks came right after a day White House issued a letter that notified the Democrats of an uncooperative stance of the administration in relation to their efforts to remove the President from office.

“You have designed and implemented your inquiry in a manner that violates fundamental fairness and constitutionally mandated due process,” White House Counsel Pat Cipollone wrote in the letter to House Speaker Nancy Pelosi, House Intelligence Committee Chairman Adam Schiff, Oversight and Reform Committee Chairman Elijah Cummings and Foreign Affairs Committee Chairman Eliot Engel.

“This letter is manifestly wrong, and is simply another unlawful attempt to hide the facts of the Trump Administration’s brazen efforts to pressure foreign powers to intervene in the 2020 elections,” Pelosi said in a statement.

Pelosi formally launched the impeachment inquiry last month after revelations Trump pressured Ukraine’s President Volodymyr Zelensky in a July 25 phone call. Biden, the former vice president who is seeking the 2020 Democratic nomination, joined the chorus of condemnation, tweeting that Trump “must stop stonewalling Congress.”

The comments marked the first time the president outlined specific conditions for his participation, putting pressure on House Speaker Nancy Pelosi (D., Calif.) to respond as the two leaders battle over how to proceed over an impeachment inquiry that stems from the Republican president’s dealings with Ukraine.

Democrats are investigating Trump’s effort to have Ukraine probe former Vice President Joe Biden, who is seeking the Democratic presidential nomination, and other election-related matters. Joe Biden called for Trump to be impeached, joining nearly all of his fellow Democratic candidates.

The House inquiry focuses on Trump’s efforts to press the president of Ukraine on the subject in a July 25 phone call.

The call, and the events leading up to it were the focus of a whistleblower complaint by an officer of the Central Intelligence Agency who alleged that Trump abused his power by targeting political rivals.

Trump has denied any wrongdoing related to Ukraine and called the impeachment effort a “kangaroo court.”