 -- The ranking member of the House Oversight Committee said he has a document that appears to show Mike Flynn, who was forced to resign as President Trump's national security adviser, lied to investigators conducting his security clearance review.

In a letter today to the committee's Chairman Jason Chaffetz, R-Utah, Rep. Elijah Cummings, D-Md., urged him to subpoena the White House for documents that detail its process for vetting Flynn.

While the White House has largely blamed the Obama administration for failing to vet Flynn, Cummings, citing investigators' records, claims Flynn lied to officials who interviewed him in February 2016 as part of his security clearance renewal.

According to the document, Flynn told investigators his trips to Russia and other countries were paid for by American companies. He has publicly claimed he was paid by a speakers' bureau for his appearance at a Moscow gala for Russian-government-funded television channel RT, but documents previously obtained by the committee indicate that RT paid Flynn more than $45,000 for his 2015 appearance.

"Gen. Flynn had a duty to be truthful on his security clearance renewal form and during his interview with security clearance investigators," Cummings said in his letter to Chaffetz, which quoted the report.

According to the investigators' report, Flynn also claimed he had "insubstantial contact" with foreign nationals, though he sat at the same table as Russian President Vladimir Putin.

"It is difficult to understand how Gen. Flynn could have believed that his dinner with Russian President Vladimir Putin was 'insubstantial contact,'" Cummings wrote.

The letter from Cummings came hours after Flynn refused to comply with a subpoena from the Senate Intelligence Committee investigating Russian interference in the 2016 presidential election. The panel had requested documents from Flynn.

"While we recognize Gen. Flynn's constitutional right to invoke the Fifth Amendment, we are disappointed he has chosen to disregard the committee's subpoena request for documents relevant and necessary to our investigation," Sens. Richard Burr, R-N.C., and Mark Warner, D-Va., said in a statement. "We will vigorously pursue Gen. Flynn's testimony and his production of any and all pertinent materials pursuant to the committee's authorities."

An aide to Chaffetz declined to comment on the letter.

Flynn's attorney has declined multiple requests for comment today from ABC News.

ABC's Matthew Mosk contributed to this report.