(CNN)House Democrats say they plan to subpoena the White House on Friday for a host of documents as part of the House's impeachment inquiry into President Donald Trump and Ukraine.

       The subpoena threat to the White House escalates the impeachment investigation from House Democrats fueled by the US intelligence community's inspector general's review of a whistleblower complaint alleging President Donald Trump sought help from Ukraine's government to interfere in the 2020 elections. Wednesday's announcement follows subpoenas to Secretary of State Mike Pompeo and Trump's personal attorney Rudy Giuliani.

       House Oversight Chairman Elijah Cummings, who is issuing the subpoena as part of the probe along with the Intelligence and Foreign Affairs Committees, sent a memo to members saying the subpoena was being issued after the White House would not provide documents.

       "The White House's flagrant disregard of multiple voluntary requests for documents—combined with stark and urgent warnings from the Inspector General about the gravity of these allegations—have left us with no choice but to issue this subpoena," the memo reads.

       The subpoena includes requests for documents related to Trump's July 25 call with Ukrainian President Volodymyr Zelensky, as well as the holding up of Ukrainian foreign aid.

       The memo, which noticed Cummings planned to issue a subpoena Friday, comes as several House committees are bracing for a last-minute briefing from the State Department's Inspector General.

       Cummings said that the "committees are investigating the extent to which President Trump jeopardized national security by pressing Ukraine to interfere with our 2020 election and by withholding security assistance provided by Congress to help Ukraine counter Russian aggression, as well as any efforts to cover up these matters."

       The memo, which noticed Cummings planned to issue a subpoena Friday, comes as several House committees are bracing for a last-minute briefing from the State Department's Inspector General.

       Cummings said that the "committees are investigating the extent to which President Trump jeopardized national security by pressing Ukraine to interfere with our 2020 election and by withholding security assistance provided by Congress to help Ukraine counter Russian aggression, as well as any efforts to cover up these matters."