(CNN) A White House staff member has told House investigators that senior officials have overruled concerns raised about 25 individuals whose security clearances were initially denied over a range of disqualifying issues -- such as fears about foreign influence and potential conflicts-of-interests -- warning of the grave implications to national security, according to a senior Democratic lawmaker.

Now House Oversight Chairman Elijah Cummings plans to issue a subpoena this week demanding an interview with Carl Kline, who served as the personnel security director at the White House during President Donald Trump's first two years in office -- as part of the Democrats' investigation into the handling of the security clearance process, including for Trump's son-in-law, Jared Kushner, and the President's daughter, Ivanka Trump, who are both also White House advisers.

In an interview Monday night, Cummings called the situation at the Trump White House "a million times worse" than the controversy involving Hillary Clinton and her use of a private email system while she was secretary of state.

"Because what you have here are people who literally have the top secrets of the world ... and they have not been properly cleared, but even more dangerous than that ... the recommendations have gone out to say they shouldn't have," the Maryland Democrat told CNN. "And so that should alarm each and every American."

Cummings released a memo Monday detailing an interview with Tricia Newbold, a White House employee who has worked for 18 years in Republican and Democratic administrations and currently serves as the Adjudications Manager in the Personnel Security Office. According to the memo, Newbold, whom Cummings described as a whistleblower, alleges that the White House has overturned the denials of 25 individuals, including two current senior White House officials, saying those decisions were occurring "without proper analysis, documentation, or a full understanding and acceptance of the risks."

"According to Ms. Newbold, these individuals had a wide range of serious disqualifying issues involving foreign influence, conflicts of interest, concerning personal conduct, financial problems, drug use, and criminal conduct," Democratic committee staff write in the memo.

A source familiar with Newbold's case told CNN Kushner and Ivanka Trump are on the list of 25 individuals.

The interview took place on March 23.

During a full day of questioning before Democratic and Republican staff on the committee, Newbold aired out an array of concerns about the security clearance process, saying that the White House had stopped doing credit history checks during the review process, lacked security for personnel files and adequate staff during the review process, and allowed for an "unusually high" number of interim security clearances, including for some individuals "who were later deemed unsuitable for access to classified information," according to the memo. And Newbold contended White House officials retaliated against her because she would not easily greenlight security clearances, alleging they sought to "humiliate her" because of her "rare form of dwarfism" by placing personnel security files she needed out of her reach.

"I would not be doing a service to myself, my country, or my children if I sat back knowing that the issues that we have could impact national security," Newbold told the committee, according to the memo.

Newbold's lawyer says she does not have official whistleblower protection because her case is still making its way through the Office of Special Counsel adjudication, which can take a long time. The lawyer, Ed Passman, says there's no such thing as official whistleblower protection but that the office can offer some protections.

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

In a letter to Cummings obtained by CNN, Kline's attorney Robert Driscoll asked the Oversight Committee to postpone its planned subpoena vote Tuesday.

"With my recent addition as counsel and Mr. Kline's wish to voluntarily comply, I write to respectfully ask that you please reconsider this course of action," Driscoll wrote.

He argued that instead of voting on a subpoena, Cummings should negotiate with Kline to work out an agreement on what topics could be included in the interview.

Cummings later suggested to CNN that he still intended to proceed with the subpoena.

The top Republican on the committee, Rep. Jim Jordan of Ohio, called Cummings' memo "unfortunate and disappointing" and "a partisan attack on the White House." Jordan said that GOP members were not given adequate time to prepare for the Newbold interview.

"Furthermore, the memo mischaracterizes the information shared by Ms. Newbold. For instance, the twenty-five examples of overruled recommendations by Ms. Newbold heralded by the Democrats include non-political officials such as a GSA custodian."

On Monday afternoon, Jordan's staff issued a nine-page memo rebutting Cummings, saying that the Democrats "cherry-picked" information from Newbold's interview to assert that the White House had poor procedures over national security matters. Jordan's staff argued that Newbold was unhappy with her work environment and that her main concerns centered on Kline, arguing she knew little about why specific individuals' security clearances had been denied, who overrode those denials and their rationale for doing so. The staff's memo said Newbold told the investigators that just "four to five" individuals out of the 25 had been denied clearances for "very serious reasons," saying just three were current and former employees of the White House.

"If Kline overturned only -- at most -- five clearance adjudications with very serious concerns out of 5,000, Ms. Newbold's concerns seem very overblown," the memo said.

Under the law, the President does have final say when it comes to allowing employees access to classified materials, something that Newbold acknowledged to House investigators, according to the memo.

But Cummings has raised concerns that the White House has ignored basic standards for providing security clearances, instead allowing his inner circle access to the country's innermost secrets without regard to the concerns raised by career professionals. CNN reported last month that Trump pressured senior White House officials to grant Ivanka Trump a security clearance, while The New York Times reported that Trump did the same for Kushner.

The memo does not specify the names of the individuals whose security clearances were initially denied -- only to be overruled by the White House. But it does provide some detail about situations involving two senior White House officials and another who used to work for the National Security Council.

For "senior White House official one," Newbold alleged that the individual's security clearance was denied after the background check revealed "significant disqualifying factors, including foreign influence, outside activities ... and personal conduct." But, she alleged, Kline overruled her recommendation to reject the clearance and merely noted "the activities occurred prior to Federal service," prompting concerns from another federal agency after the official applied for an even higher security clearance.

Similarly, after concerns were raised about "senior White House official two," including over the potential of foreign influence, Kline said "do not touch" the case in a conversation with Newbold, according to the memo, and the individual's security clearance was approved.

For "senior White House official three," who worked at the National Security Council, Kline told Newbold to "change the recommendation" against providing a security clearance, something she said she refused to do.

"I said I would absolutely not," Newbold told the committee.

In their rebuttal memo, Jordan's staff said Newbold had "no direct knowledge" about why Kline overruled her recommendation on the first White House official, and that she acknowledged she did not work on the second White House official's case "specifically." The Jordan memo also contended that the third White House official had never obtained a final security clearance.

Along with releasing the memo Monday, Cummings sent a letter to White House counsel Pat Cipollone, accusing the White House of stonewalling his repeated requests for information and saying he would proceed to issue a subpoena for Kline at a committee meeting Tuesday. Cummings warned that he was prepared to issue subpoenas after multiple requests for information went ignored, and said he wanted to interview a number of other officials, including former deputy chief of staff Joseph Hagin.

"In light of the grave reports for the whistleblower -- and the ongoing refusal of the White House to provide the information we need to conduct or investigations -- the Committee now plans to proceed with (the) compulsory process and begin authorizing subpoenas, starting at tomorrow's business meeting," Cummings wrote Monday.

"The Committee will depose Mr. Kline about the security clearance practices in place when he was at the White House, the treatment of specific security clearance adjudications during his tenure, and the interactions with the whistleblower," Cummings wrote.

The White House has continuously argued in their correspondence with Cummings that it had broad jurisdiction to protect security clearance information of individuals and that they had no intention to turn over personal security clearance information with the committee. The White House did provide the committee with a briefing of the administration's security clearance process and a review of "a handful of guidance documents," according to Cummings.

This story has been updated with additional developments Monday.