House Democrats plan to push forward with a probe into whether President Donald Trump played a role in hush payments to two women during the 2016 campaign who alleged decade-old affairs with him, a Democratic aide to the House Oversight Committee told NBC News.

Democrats are set to regain the House majority in January, which will give them the power to subpoena documents and witnesses as they take charge of the lower body of Congress' investigative-minded committees.

In September, Rep. Elijah Cummings of Maryland, the ranking Democrat on the House Oversight Committee, requested that then-White House counsel Donald McGahn and a top Trump Organization executive provide all documents and communications related to reimbursements made by Trump or the Trump Organization to Cohen for the payments.

At the time, Cummings also requested all documents related to Trump's two most recent financial disclosures, zeroing in on a discrepancy related to how much money Trump paid Cohen as reimbursement for his original $130,000 payment to adult-film actress Stormy Daniels.

Pointing to that letter, the Democratic aide said Democrats on the committee began probing the payments months ago, but did not receive any of the documents Cummings had requested "because we were in the minority."

The aide, who requested anonymity to speak candidly about the investigation, added, "This should change now that we are in the majority."

The Wall Street Journal first reported on Democratic efforts to ramp up this probe. Trump's personal attorney, Rudy Giuliani, and the Trump Organization did not immediately return requests for comment from NBC News.

Both Daniels and former Playboy model Karen McDougal alleged affairs with the president, which he has denied. Cohen, who pleaded guilty in federal court this year to two campaign finance violations stemming from the payments, paid Daniels $130,000 just weeks before the 2016 presidential election so she would stay silent about her allegations. Cohen told a federal judge during his guilty plea that Trump directed him to make such payments.

Trump has said Cohen is not credible.

American Media Inc., which publishes The National Enquirer, paid McDougal $150,000 in August 2016 to buy her story of a Trump affair. The National Enquirer never published the story. The Journal reported Friday that Trump in 2015 asked Pecker, a longtime friend, to help his campaign. In response, Pecker suggested he could offer to buy off women who may come forward with allegations of affairs with Trump.

In that Friday article, The Journal reported that Trump was involved in or briefed on nearly every step of the hush money agreements that Cohen helped arrange. Trump has denied any knowledge of the deals from the time they were reached.