(CNN) House Democrats on Friday issued a subpoena to the White House for documents related to Ukraine, ratcheting up the Democratic impeachment inquiry into President Donald Trump.

The subpoena came after the three committees leading the impeachment inquiry separately sent a letter Friday seeking documents from Vice President Mike Pence as part of their investigation into Trump and his conversation with the President of Ukraine.

The subpoena from House Oversight Chairman Elijah Cummings to the White House includes a request for a host of documents and communications tied to the President's July 25 call with Ukrainian President Volodymyr Zelensky, the holding up of foreign aid to Ukraine and efforts by Trump's personal lawyer Rudy Giuliani and his associates to push the Ukrainians to investigate Vice President Joe Biden and Burisma, the company that hired Hunter Biden's son Hunter Biden to be on its board, according to a memo Cummings sent on the subpoena earlier this week.

"We deeply regret that President Trump has put us — and the nation — in this position, but his actions have left us with no choice but to issue this subpoena," Cummings of Maryland, House Intelligence Chairman Adam Schiff of California and House Foreign Affairs Chairman Eliot Engel of New York wrote in a letter to the White House on Friday.

The subpoena escalates the Democratic impeachment investigation, which stems from the whistleblower complaint alleging Trump sought help from Ukraine's government to dig up dirt on his political rival and the White House sought to cover it up. The three panels leading the probe have already issued subpoenas to Secretary of State Mike Pompeo and Giuliani, in addition to Friday's White House subpoena.

The White House downplayed the subpoena.

"This subpoena changes nothing -- just more document requests, wasted time, and taxpayer dollars that will ultimately show the President did nothing wrong," press secretary Stephanie Grisham said in a statement. "The Do Nothing Democrats can continue with their kangaroo court while the President and his Administration will continue to work on behalf of the American people."

The request for documents to Pence, meanwhile, adds the vice president to a growing list of Trump officials and allies from who Democrats are seeking documents as part of the impeachment inquiry.

The three chairmen leading the probe wrote a letter to Pence on Friday requesting the documents by October 15. A subpoena could also be looming for Pence if he does not voluntarily provide the documents.

Rather than traveling to Warsaw, Poland, last month to meet with Ukrainian President Volodymyr Zelensky, Trump decided to stay home to track the damage from Hurricane Dorian. In his place he sent Pence, whose face-to-face meeting with Zelensky now puts him at the heart of events that led to the impeachment inquiry by the House of Representatives.

The Democratic impeachment investigation stems from the whistleblower complaint alleging Trump sought help from Ukraine's government to dig up dirt on his political rival and the White House tried to cover it up.

House Democrats have set an aggressive schedule of depositions to go along with their document requests as they have prepared to potentially file articles of impeachment related to Ukraine, putting the other matters they were investigating involving the President -- from Russian election interference to the Emoluments clause of the Constitution -- to the side.

The vice president's spokesman said that the Democrats letter "does not appear to be a serious request."

"Given the scope, it does not appear to be a serious request but just another attempt by the Do Nothing Democrats to call attention to their partisan impeachment," Pence spokeswoman Katie Waldman said in a statement. "Despite their efforts to distract and obstruct our agenda, this Administration will stay focused on creating jobs, securing the border, rebuilding our military, negotiating better trade deals, and the issues most important to the American people."

The Trump administration has signaled it does not intend to cooperate with the House investigation on Ukraine, just as it has stonewalled previous requests related to allegations of obstruction of justice and efforts to obtain the President's tax returns and other financial documents. Pompeo wrote in a letter this week that he would try to block State Department officials from testifying, calling the schedule unfeasible, and it was unclear whether he would comply with a subpoena that had a Friday deadline.

Trump said Friday that he would be issuing a letter to House Speaker Nancy Pelosi in response to the Democrats' request for documents. White House lawyers were drafting the letter saying they could not be compelled to produce documents until the full House votes to open an impeachment inquiry, something Pelosi has said is unnecessary according House rules.

Previously, Democrats have responded to White House stonewalling with contempt votes and lawsuits to pry loose the materials they were seeking. But they now appear to be taking a different tack with the Ukraine inquiry: arguing that a failure to cooperate will make their case that obstruction of justice occurred.

"We don't want this to drag on months and months and months, which appears to be the Administration's strategy, so they just need to know that even as they try to undermine our ability to find the facts around the President's effort to coerce a foreign leader to create dirt that he can use against the political opponent, that they will be strengthening the case on obstruction if they behave that way," Schiff said at a newsconference this week.

But the Democrats have had successes in obtaining information, too, including the testimony from former US special envoy to Ukraine Kurt Volker and text messages Volker provided showing that Trump's push for an investigation was linked to Ukraine's efforts to obtain a face-to-face meeting between the two presidents.

Pence was told about the July 25 call between Trump and Zelensky a day after it occurred, sources told CNN, although they would not say whether the vice president was briefed about what Trump said about the Bidens.

This story has been updated with additional developments Friday.