The more undisciplined President Donald Trump becomes in his scattershot defenses of his behavior toward Ukraine, the more robotically Vice President Mike Pence seems to stay on message. Unfortunately, that message is an indefensible falsehood. During a television interview Monday with PBS' Judy Woodruff, Pence said three times that anyone who reads the rough transcript of Trump's July 25 phone call with Ukrainian President Volodymyr Zelensky "will see the president did nothing wrong. There is no quid pro quo."

The interview left us with the sense that Pence himself has not carefully read the document. As we pointed out in an editorial on Sept. 25, the day it was released, the transcript ends with a clear exchange of commitments between the U.S. and Ukrainian presidents. Zelensky promises to launch the investigations Trump had just requested of Joe Biden and the Democratic National Committee; Trump responds by offering the invitation to the White House Zelensky was seeking.

More to the point, Pence appears determined to ignore the sworn testimony of senior officials who have since confirmed the quid pro quo that the White House claims doesn't exist. The latest was National Security Council official Lt. Col. Alexander Vindman, who told Congress on Tuesday that he attended a July 10 meeting with a senior Ukrainian official at which an ambassador appointed by Trump, Gordon Sondland, "started to speak about Ukraine delivering specific investigations in order to secure the meeting with the president."

To his credit, Lt. Col. Vindman told Sondland that "his statements were inappropriate, that the request to investigate Biden and his son had nothing to do with national security," a judgment he said was echoed by his boss, NSC senior director Fiona Hill. Both later reported their concerns to the NSC general counsel.

That makes at least five officials who have described the quid pro quo in congressional testimony. That includes the United States' acting ambassador in Kyiv, William Taylor Jr., who said Sondland told him U.S. military aid was also linked to Trump's political demands; Kurt Volker, the former special envoy to Ukraine, who provided text messages spelling out the deal; and Sondland himself, who, according to his lawyer, told House investigators that while Trump had denied any quid pro quo, Sondland — who spoke to the president directly about the matter — believed there was one.

Pence dismissed all this evidence on the grounds that it was "leaks" from secret hearings; never mind that most of the officials released their own opening statements. He criticized House Democrats for failing to hold a formal vote on impeachment proceedings and for not releasing the transcripts of testimony, even though they have announced they will do both. He seemed to believe that by mindlessly repeating the words "no quid pro quo" he could disappear the increasingly powerful case that Trump abused his office.

He can't — and nor will slander of the witnesses by Trump's more vulgar surrogates. On Tuesday, former congressman Sean Duffy, R-Wis., shamelessly suggested that Lt. Col. Vindman, a refugee from the former Soviet Union, might be more loyal to Ukraine than the United States. GOP law professor John Yoo hinted the Purple Heart recipient might be implicated in espionage. Such vile slurs only underline the absence of any legitimate defense for Trump's actions.

This editorial is the opinion of The Washington Post's editorial board.