WASHINGTON – As President Donald Trump attacked House Democrats on Tuesday for launching various investigations against him, White House lawyers set up the prospect of a subpoena fight by rejecting a request for documents on security clearances.

The House committee seeking the documents "has failed to point to any authority establishing a legitimate legislative purpose" for its "unprecedented and extraordinarily intrusive demands," said a letter from White House Counsel Pat Cipollone.

Rep. Elijah Cummings, D-Md., chairman of the House Committee on Oversight and Reform, cited reports that Trump granted a top level security clearance to senior adviser and son-in-law Jared Kushner despite concerns raised by national security aides.

"There is a key difference between a president who exercises his authority under the Constitution and a president who overrules career experts and his top advisors to benefit his family members and then conceals his actions from the American people," Cummings said.

Cummings said he would consult with other committee member about "our next steps," which could include a subpoena.

The document battle, likely the first of many between White House aides and House Democrats, erupted as Trump criticized his political opponents by saying they are more interested in the 2020 presidential campaign than in helping the country.

"Instead of doing infrastructure, instead of doing health care … they want to play games," Trump told reporters after signing an executive order instituting a plan to reduce suicides by veterans.

A day after the House Judiciary Committee made document requests of 81 agencies, entities, and individuals associated with Trump, the president called the probe "a disgrace to our country" that has more to do with presidential politics.

“They could not stand losing in 2016 .. the anger, the anger," Trump said. "Essentially what they're saying is, the campaign begins."

Nadler:House Judiciary Chair Jerry Nadler says it's 'clear' Trump obstructed justice, plans 'abuse of power' probe

The investigation:See the full list of 81 Trump associates asked for documents by House Judiciary Democrats

Trump did not say whether his administration plans to comply with the document requests.

Rep. Jerrold Nadler, D-N.Y., chairman of the House Judiciary Committee, said it is looking into allegations in three basic areas: Obstruction of Justice, public corruption, and abuses of power.

Because Republicans controlled the House the past two years, Nadler said, Trump "has evaded accountability for his near-daily attacks on our basic legal, ethical, and constitutional rules and norms."

Examples range from attacks on the press to alleged interference in the investigation by special counsel Robert Mueller into efforts to influence the 2016 presidential election.

"Congress must provide a check on abuses of power," Nadler said.