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The House Oversight Committee is launching an investigation into the White House security clearance process, an inquiry that promises to put a spotlight on how President Donald Trump's senior adviser and son-in-law, Jared Kushner, overcame concerns to gain access to highly classified information.

"The Committee on Oversight and Reform is launching an in-depth investigation of the security clearance process at the White House and Transition Team in response to grave breaches of national security at the highest levels of the Trump administration," Rep. Elijah E. Cummings, the chairman of the Committee on Oversight and Reform, said in a letter to the White House obtained by NBC News.

The White House did not immediately respond to a request for comment.

Last February, NBC News reported that more than 130 political appointees working in the Executive Office of the President did not have permanent security clearances as of November 2017, including the president's daughter Ivanka; Kushner, her husband; and the president's top legal counsel. Kushner has since obtained a clearance, according to his lawyer, despite reports that he has been targeted for manipulation by foreign governments.

Cummings said he is seeking documents relevant to the NBC news report.

Kushner's clearance was downgraded last February after it emerged that he initially failed to submit required information on his financial disclosure form. He regained full clearance a few months later, his lawyer said, but White House and CIA officials declined to discuss the circumstances.

According to The Washington Post, Kushner was granted only "top secret" status, a designation that bars him from reviewing some of the government's most closely guarded intelligence.

In the letter, Cummings said the investigation will seek to determine "why the White House and Transition Team appear to have disregarded established procedures for safeguarding classified information" and "the extent to which the nation's most highly guarded secrets were provided to officials who should not have had access to them."

Last year, Cummings pointed out, John Kelly, Trump's chief of staff, acknowledged "shortcomings" with the White House's security clearance process.

Kelly warned that the White House "should — and in the future, must — do better," and added that "now is the time to take a hard look at the way the White House processes clearance requests."

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But the White House has said nothing about any changes made to the process, and has rebuffed congressional requests for information, Cummings said.

"For the past two years, I have sought information with other Committee Members about a series of extremely troubling incidents regarding the security clearances of some of President Trump's top aides, but the White House has refused to provide the information we requested, often ignoring our requests completely," Cummings said.

Rep. Elijah Cummings speaks to reporters at the Capitol on Jan. 4, 2019. J. Scott Applewhite / AP file

Cummings' letter seeks information about reports of security clearance issues involving multiple current and former officials, including:

• Senior adviser to the president Jared Kushner

• National security adviser John Bolton

• Former national security adviser Michael Flynn

• Flynn's son, Michael Flynn Jr.

• Former deputy national security adviser K.T. McFarland

• Former White House staff secretary Robert Porter

• Former National Security Council senior director Robin Townley

• Trump's former personal assistant, John McEntee

• Former deputy assistant to the president Sebastian Gorka

Cummings said he also sent a letter to the National Rifle Association about Bolton, seeking information about his contacts with Maria Butina, an NRA member who has been charged as an unregistered agent of Russia.

Cummings said he is demanding documents relating to Kelly's review of security clearance processes in 2018, and the NBC report that 34 White House officials who had started working on the first day of the Trump administration were still working with interim security clearances as of November 2017 and that more than 130 political appointees in the Executive Office of the President were working with interim security clearances as of that date.

Cummings also asked for documents pertaining to what he said is the White violation of the SECRET Act — a law requiring the White House to submit a report to Congress by August 2018 on its procedures for adjudicating security clearances.

Cummings sent similar letters Wednesday to Vice President Mike Pence in his capacity as chair of the transition team, the Federal Bureau of Investigation, the Department of State and the National Rifle Association.

House Republicans had launched an investigation into security clearances in February 2018, after questions about how Porter, who had been staff secretary, had been given access to top secret code-word information despite domestic violence allegations against him.

But the White House defied the GOP-controlled committee's requests for information and no action was taken.

Democrats have vowed to issue subpoenas if the Trump administration fails to turn over documents in response to requests from committee chairman.