WASHINGTON — House Democrats and President Trump are not just fighting over the Mueller report.

More than 20 congressional investigations have been hampered by the Trump administration, according to House Judiciary Chairman Jerrold Nadler (D-NY).

“By this administration’s command, the White House has attempted to impede over 20 congressional investigations, including by ignoring or failing to provide meaningful responses to dozens of letters requesting information on topics ranging from the Affordable Care Act, to the security of our elections, to the policy of separating children from their parents at the border,” Nadler said at the opening of a committee hearing Wednesday on executive privilege.

Nadler noted how a number of government witnesses have failed to show up for interviews and hearings.

“While in other administrations Congress issued subpoenas only as a last resort, when negotiations failed, the Trump administration has often been unwilling to engage with Congress at all, unless and until a subpoena is issued and a contempt proceeding is looming,” Nadler said.

“This constitutional brinkmanship is particularly unacceptable whereas here the president is using the powers of his office to impede an investigation into his own alleged misconduct,” the New York Democrat said.

Nadler was referring to his biggest battle with the White House — to get a copy of the full, unredacted Mueller report.

A less redacted copy of the report, which details Russian interference in the 2016 election and lays out a case for whether Trump obstructed justice, made its way to Capitol Hill, with top lawmakers of both parties allowed to see it. Democrats decided not to go view those documents out of principle as they continued to request access to the full report.

Earlier this month, Trump claimed executive privilege over the entire Mueller report.

In turn, the House Judiciary Committee brought in legal experts to testify on executive privilege Wednesday.

Nadler said he invited White House counsel Pat Cipollone to explain the administration’s point of view, but he declined to attend, and instead submitted a written statement.

Nadler didn’t read the letter during the hearing, saying that it “restates the same arguments previously raised by the Justice Department.”

In a separate letter that was also dated Wednesday, Cipollone said Nadler was duplicating the work of special counsel Robert Mueller on the Russia probe.

“The only purpose for this duplication seems to be harassing and seeking to embarrass political opponents after an exhaustive two year investigation by the Department of Justice did not reach the conclusion that some members of the committee apparently would have preferred,” Cipollone said.