This article is more than 11 months old

This article is more than 11 months old

House Democrats have subpoenaed the White House demanding documents that could shed light on Trump’s efforts to pressure Ukraine, in the latest escalation of their impeachment investigation into the president and his administration.

The move comes as the senior Democrats also formally requested documents relating to Ukraine dealings from Mike Pence, the vice-president.

The subpoena, issued late Friday, follows numerous appeals for the White House to produce documents voluntarily. The letter, addressed to the acting chief of staff, Mick Mulvaney, and signed by representatives Elijah Cummings, Adam Schiff and Eliot Engel, accuses the president of “stonewalling” and says they were left “with no choice” but to subpoena.

“It appears clear that the president has chosen the path of defiance, obstruction, and cover-up,” the letter reads, warning that failure to comply – even at the direction of the president – “shall constitute evidence of obstruction of the House’s impeachment inquiry”.

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The House investigators also want Pence to give them documents that could shed light on whether he helped Trump pressure Ukraine to investigate Joe Biden, the former vice-president and leading Democratic candidate for the 2020 nomination.

Another letter sent earlier by Schiff, Cummings and Engel – the chairs, respectively, of the House intelligence, oversight and foreign affairs committees – cites reports that a Pence aide may have listened to the 25 July phone call in which Trump pushed Ukraine’s new president – who was waiting for hundreds of millions of dollars of US military aid that had been withheld – to investigate unfounded charges that Biden was involved in corrupt activities there.

The chairmen say they also want to learn more about a meeting Pence had on 1 September with Volodymyr Zelenskiy, the Ukrainian president.

The letter says there are “questions about any role you may have played in conveying or reinforcing the president’s stark message to the Ukrainian president”.

The development came as Trump said the White House was also preparing a letter – this one to the House speaker, Nancy Pelosi. Its intention is to formally object to the Democrats commencing their impeachment inquiry without an official vote on it in Congress – but admits that if a vote were held he believes it would pass.

The letter is expected to say the administration will not cooperate with the inquiry without that vote. Trump acknowledged that Democrats in the House “have the votes” to begin a formal impeachment inquiry, but said he is confident they do not have the votes to convict in the Republican-controlled Senate.

“We’ll be issuing a letter. As everybody knows, we’ve been treated very unfairly, very different from anybody else,” he said.

The move appears to represent a fresh attempt to undermine and frustrate the impeachment inquiry, and comes after the explosive release of text messages between US diplomats and an assistant to Zelenskiy. The exchanges discuss Zelenskiy being told that a prestigious White House visit to meet Trump was dependent on him making a public statement vowing to investigate Hunter Biden, Joe’s son, and lending credence to a Trump conspiracy theory about a Ukrainian role in the 2016 elections.

Trump openly called on China and Ukraine to investigate the Bidens this week, but he continued to deny wrongdoing on Friday, repeating his refrain there was no “quid pro quo” attached to the requests. The text messages reveal that this was not the understanding of US diplomats dealing with Ukraine.

In a tweet, Trump said the presidency gave him “an absolute right, perhaps even a duty, to investigate or have investigated, CORRUPTION, and that would include asking, or suggesting, other Countries to help us out!”

In response, Schiff, the intelligence committee chair, tweeted: “It comes down to this. We’ve cut through the denials. The deflections. The nonsense. Donald Trump believes he can pressure a foreign nation to help him politically. It’s his “right.” Every Republican in Congress has to decide: is he right?”

On Friday, the White House press secretary, Stephanie Grisham, said the House impeachment inquiry subpoena “changes nothing – just more document requests, wasted time and taxpayer dollars that will ultimately show the president did nothing wrong”.

Trump, senior Republicans and prominent conservative media figures are either counter-attacking or remaining silent.

Most Republican senators remained quiet on Friday, but the 2012 presidential candidate and current Utah senator Mitt Romney issued a statement that said “the president’s brazen and unprecedented appeal to China and to Ukraine to investigate Joe Biden is wrong and appalling”.

As the impeachment scandal continues to escalate, the House intelligence committee, one of six that are holding impeachment hearings into Trump’s conduct, questioned the intelligence community inspector general, Michael Atkinson, behind closed doors.

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Republicans are aggressively questioning the absence of an official vote on impeachment prior to the inquiry formally beginning.

In announcing that the House was beginning the investigation, Pelosi did not seek the consent of the full chamber, as was done for impeachment investigations into former presidents Richard Nixon and Bill Clinton.

Pelosi swatted it back as unnecessary, saying the House is well within its rules to pursue the inquiry without taking a vote.

“The existing rules of the House provide House committees with full authority to conduct investigations for all matters under their jurisdiction, including impeachment investigations,” Pelosi wrote Thursday in a letter to the House Republican leader Kevin McCarthy after he, too, pressed for a floor vote.

Pelosi has sought to avoid a vote on the impeachment inquiry for the same reason she resisted, for months, liberal calls to try to remove the president: it would force moderate House Democrats to make a politically risky vote.

Agencies contributed reporting