The White House has told Carl Kline, the former security specialist who approved Jared Kushner’s security clearance over the objections of career staffers, not to comply with a subpoena from the House Oversight Committee, according to a letter obtained by NBC News.

Kline was supposed to appear before committee staff Tuesday to face questions related to his handling of White House security clearances.

But in a letter to Kline's attorney Robert Driscoll dated Monday, White House Deputy Counsel Michael Purpura said Kline should not appear for an interview if the committee does not allow a member of the White House counsel staff to attend.

Driscoll sent his own letter to the committee, saying that Kline risked jeopardizing his job at the Pentagon if he defied the White House. "This decision is not made lightly and does not come from any ill will or deliberate defiance on my part or that of my client," Driscoll wrote to congressional staffers.

"With two masters from two equal branches of government, we will follow the instructions of the one that employs him," Driscoll added.

Rep. Elijah Cummings, D-Md., the chairman of the House Oversight and Government Reform Committee, said he plans to speak with his members about scheduling a vote to hold Kline in contempt for defying the subpoena.

“The White House and Mr. Kline now stand in open defiance of a duly authorized congressional subpoena with no assertion of any privilege of any kind by President Trump," Cummings said in a statement.

"Based on these actions, it appears that the president believes that the Constitution does not apply to his White House, that he may order officials at will to violate their legal obligations, and that he may obstruct attempts by Congress to conduct oversight."

Cummings noted that the White House wrote to his committee last Thursday threatening to order Kline to skip the scheduled deposition unless the White House counsel was allowed to participate. Four days later, Cummings said, the committee responded by explaining that it has for many years prohibited agency lawyers from participating in depositions.

NBC News reported in January that two White House security specialists recommended that Kushner not receive a top secret security clearance after they reviewed his clearance application and deemed it to be "unfavorable." But according to sources familiar with the matter, Kline took the unusual step of overruling career staff to approve Kushner's top secret clearance.

After Kushner was approved by Kline, his application went to the CIA for an even higher level of clearance known as “sensitive compartmented information," or SCI, according to two sources familiar with the matter. But officers reviewing the decision at the CIA balked. One called over to the WH security division wondering how Kushner had even obtained a top secret clearance, the two sources said.

The sources say the CIA has not granted Kushner clearance to review SCI material. That would mean Kushner lacks access to key intelligence unless President Donald Trump decides to override the rules, which is the president's' prerogative.

Kline also approved security clearance applications of 25 others working for the Executive Office of the President over the objections of career personnel, according to an interview the House Committee staff conducted with White House security specialist Tricia Newbold and other sources familiar with the matter.

Kline has also been accused by Newbold of discrimination against her because of her height. Newbold, who has a rare form of dwarfism, charges that Kline repeatedly moved files out of her reach.

In an interview with NBC News this month, Newbold said, "It was definitely humiliating ... but it didn't stop me from doing what was right."