The president is counting on the loyalty of subordinates who will face growing pressure to testify, and analysts say that’s risky

In the opening exchanges of the impeachment inquiry against him, Donald Trump has adopted a hardline strategy of angrily denying congressional requests for documents and testimony and attacking the proceedings as illegitimate. Analysts say this is risky.

Clear majority of Americans support Trump impeachment inquiry, poll finds Read more

For now, a Republican majority in the Senate insulates Trump against the threat of removal from office. But that advantage does not appear to be guiding the president’s hand.

In contrast with Bill Clinton’s deflect-and-minimize approach, Trump has taken a more Richard Nixon-like route, treating impeachment as an existential attack and digging in for a gunfighter’s last stand.

It is a strategy with little margin for error, analysts say, with Trump depending all at once on keeping public approval behind him, on blocking myriad avenues by which Congress might collect evidence and, crucially, on retaining the loyalty of subordinates who will come under increasing pressure to testify.

A major poll released on Tuesday indicated that Trump might be miscalculating badly about public opinion. A 58% majority now support the inquiry versus 38% who oppose it, the Washington Post-Schar School poll found. Support for an impeachment inquiry has grown 20 points in three months, the poll found.

Let them hold me in contempt. We’ll go to court. We’ll challenge the contempt Rudy Giuliani

Regardless, Trump redoubled his strategy of stonewalling, blocking the testimony at the last minute of Gordon Sondland, the ambassador to the European Union who had flown to Washington to tell Congress what he knew about the president’s efforts to pressure Ukraine to announce investigations Trump could use against Joe Biden. Those efforts are at the core of the impeachment inquiry.

Sondland was prepared to exonerate Trump, the president tweeted, “but unfortunately he would be testifying before a totally compromised kangaroo court”.

In a statement issued by his lawyer, Sondland, a hotelier whose support for Trump wavered during the last presidential primary, sent a different message.

“Ambassador Sondland is profoundly disappointed that he will not be able to testify today,” the statement said. “He stands ready to testify on short notice, whenever he is permitted to appear.”

Hours later, congressional Democrats said Sondland had been blocked from testifying by a voicemail from superiors in the state department left at 12.30am. They announced they would subpoena Sondland’s testimony and his personal messages, ratcheting up the stakes.

The blocking of Sondland is part of a wagon-circling throughout the executive branch. On Friday, the secretary of state, Mike Pompeo, missed a deadline to turn over documents. Congress has also issued subpoenas to the White House, the defense department and the Office of Management and Budget. Vice-President Mike Pence also faces a documents request.

Rudy Giuliani, Trump’s personal lawyer, announced on Tuesday he would defy a congressional subpoena and said: “The position I’m stating is now the position of the administration.

“Let them hold me in contempt,” Giuliani told the Washington Post. “We’ll go to court. We’ll challenge the contempt.”

The non-appearance of Sondland would only accelerate proceedings, said Adam Schiff, chair of the House committee leading the impeachment inquiry.

“The failure to produce this witness, the failure to produce these documents, we consider yet additional strong evidence of obstruction of the constitutional functions of Congress,” Schiff said.

Even if Trump’s stonewalling damages the ability of Democrats to collect evidence in the short term it could add to the case against him, said Bradley P Moss, a national security lawyer.

Someone should tell Donald Trump that you can definitely be impeached for obstruction of justice Kamala Harris

“Although it arguably would be better from a factual record standpoint to have all relevant fact witnesses testify and produce relevant documentation,” Moss wrote in an email, “if the House Democrats believe they have enough evidence already to proceed to impeachment, they can simply lump in the White House’s refusal to let witnesses testify into an all-encompassing ‘obstruction’ article of impeachment and throw that on the pile with everything else.”

Kamala Harris, a California senator and candidate for the Democratic presidential nomination, tweeted: “Someone should tell Donald Trump that you can definitely be impeached for obstruction of justice.”

Trump’s reliance on the loyalty of subordinates also could represent a strategic misstep – because former officials are already talking.

After resigning, Kurt Volker, the former special envoy to Ukraine, last week delivered to Congress pages of WhatsApp messages between himself and other diplomats that damaged Trump’s efforts to characterize his negotiations on Ukraine.

Schiff has said he wants to speak with another diplomat, Bill Taylor, who wrote in the message exchange: “I think it’s crazy to withhold security assistance for help with a political campaign.”

Facebook Twitter Pinterest Adam Schiff said he would subpoena Gordon Sondland for documents and testimony. Photograph: Shawn Thew/EPA

In a piece on the Just Security site comparing proceedings against Nixon, Clinton and Trump, the former Clinton aide and impeachment trial witness Sidney Blumenthal noted that Nixon’s resistance to Congress accelerated his decline.

“When the Senate Watergate hearings began, Nixon’s standing in public opinion began to erode, a decline accelerated at each stage by his stonewalling of Congress and the courts,” Blumenthal wrote.

By refusing subpoenas and blocking testimony, the White House appears to hope to slow the process down. Trump loyalist Jim Jordan, a House Republican from Ohio, launched an attack on Tuesday against “the Democrats’ reckless haste”. Th Republican senator Lindsey Graham announced a new inquiry that would seek testimony from Giuliani and could compete with the House inquiry in the public mind.

In terms of public support, Trump does not have nearly so far to fall as Nixon did at a similar juncture.

It took five months of hearings against Nixon before public approval for the process hit 58%, noted Greg Dworkin, an editor at the liberal Daily Kos.

Impeachment proceedings against Trump are only two weeks old.