Ivanka Trump boards Air Force One at Joint Base Andrews in Maryland on June 26. (Brendan Smialowski/AFP/Getty Images)

House Democrats are asking the White House for copies of all work communications sent via personal email, personal cellphone and other forms of nonofficial transmission in an expansion of their investigation into whether Trump administration officials violated federal record-keeping laws.

The House Oversight Committee on Monday said the step was necessary “after six months of White House stonewalling” on the matter. This year, Chairman Elijah E. Cummings (D-Md.) asked the administration about reports that some top White House officials — including President Trump’s daughter Ivanka Trump and son-in-law Jared Kushner — used personal email and encrypted applications to communicate.

Such communications are against record-keeping laws unless they are forwarded to and stored on official channels. The White House, however, has refused to tell the committee about the results of its own internal investigation of the matter, Democrats say. The panel wants copies of all emails that did not comply with this law.

“Unfortunately, over the past six months since I sent my letter, you have not produced a single document, you have not provided any of the requested briefings, and you have not offered any timeline by which these requests will be fulfilled,” Cummings wrote in a letter to White House counsel Pat Cipollone. “The White House’s complete obstruction of the committee’s investigation for the past six months is an affront to our constitutional system of government.”

Former secretary of state Hillary Clinton’s use of private email for government business was a major issue in the 2016 campaign. Then-candidate Donald Trump repeatedly criticized Democratic rival Clinton for her use of a private email server. In recent months, the White House has refused to give House Democrats information about similar issues that have arisen in the Trump administration.

If past is prologue, the panel is unlikely to receive the emails it seeks. The Trump administration repeatedly has blocked congressional oversight, and the White House is unlikely to comply with the request.

That means Democrats will have to decide once again whether to subpoena information to which they believe they are entitled. The chamber already is looking to the courts to enforce several subpoenas the administration has ignored, a process that could take months if not years.

Democrats on the committee also are unlikely to receive assistance from their GOP counterparts on the Oversight panel, who have become some of Trump’s top allies on Capitol Hill. During the last Congress, however, the previous Oversight chairmen, Reps. Jason Chaffetz (R-Utah) and Trey Gowdy (R-S.C.) — both now retired — joined with Democrats to raise alarms about reports of personal email use in the White House.

In addition to reports about Ivanka Trump’s and Kushner’s use of private communications for work purposes, the panel has been looking into former White House officials Stephen K. Bannon and K.T. McFarland.

Democrats in a news release Monday noted that former special counsel Robert S. Mueller III wrote in his report that Bannon in particular said he “regularly used his personal Blackberry and personal email for work-related communications, and he took no steps to preserve these work communications.”