Rudy Giuliani on Wednesday refused to say what sort of agreement, if any, he has with President Donald Trump to act as his lawyer.

“If I did, I wouldn’t show it to you, and what right do you have to ask me that?” Giuliani said in a phone call with BuzzFeed News. “I’m a private lawyer. I could have a handshake with him. I don’t have to tell you what the basis of my attorney-client relationship is.”

A whistleblower complaint that prompted House Democrats to launch a formal impeachment inquiry into the president called Giuliani a “central figure” in Trump’s alleged efforts to pressure Ukrainian President Volodymyr Zelensky to investigate Joe Biden and the 2016 election.

Giuliani, who traveled around the world meeting with foreign officials, has said he is working pro bono for Trump, and said last week that the president did not pay his travel expenses. He hedged that statement by adding, “What does it matter if I’m getting paid for it?”

Speaking to BuzzFeed News, Giuliani grew agitated when asked about the details of his work with Trump. “It’s been announced, it was announced when it happened, it’s public, everybody knows it. What kind of nitpicking is that?”

“You have no right to see it,” he said, though he was only asked if the agreement existed. “You have no right to ask about it.”

(Lawyers licensed to practice in New York — as Giuliani is — generally are required to provide a “letter of engagement” to a client about the scope of legal services they’ll perform and what fees and expenses they’ll charge, although there are exceptions. Attorney-client agreements aren’t public.)

The nature of Giuliani’s work for Trump is central to how congressional investigators are able to gather information from Giuliani. If Giuliani has been working as the president’s personal lawyer, he could claim attorney-client privilege over his communications with the president in an attempt to keep at least some of that information private. But there are exceptions to that privilege, and Giuliani himself recently told the Atlantic, “I’m not acting as a lawyer.”

House Democrats subpoenaed Giuliani on Monday. When asked if he would comply, Giuliani said “I have not made a decision.” He then attempted to argue that invoking attorney-client privilege with Trump was a form of compliance.

“For anyone to describe not complying by raising attorney-client privilege is a complete trashing of the US Constitution,” he said. “When has the attorney-client privilege not been a sufficient objection to a demand subpoena where you’re given 15 days to go through two and a half years of work, almost all of which was done to defend my client against their false charges?”

He repeated that he was considering suing House Democrats. “That’s why I’m considering, seriously, a lawsuit against them, both as the House Democrats and as individuals for violating constitutional rights and civil rights and having deliberately put together two false claims against the president,” specifying that the first referred to “Russian collusion” and the second to Biden. He did not name names, but he had previously referred to House Intelligence Committee Chair Adam Schiff and Judiciary Committee Chair Jerry Nadler

Giuliani has accused Biden of demanding the firing of a Ukrainian prosecutor over an investigation into his son Hunter’s work on the board of Ukrainian gas company Burisma. The prosecutor, Viktor Shokin, was however widely recognized as corrupt by the US government, as well as by the European Union and the International Monetary Fund.

Since launching his crusade, Giuliani has also pointed to Hunter Biden’s business dealings in China. He at first refused to discuss his efforts in the country, because this reporter had not read a book by Peter Schweizer, who has written on conspiracies surrounding both Biden and Hillary Clinton. “If you haven’t read it, don’t ask me any questions about it, because you’re not doing your job.” Asked again if he had broached the subject with officials there, he said, “I have not.”

Giuliani saved some of his loudest yelling when asked about Lev Parnas and Igor Furman, two Ukrainian Americans who were involved in Giuliani’s global effort. He repeatedly declined to answer specific questions about them, saying: “It's another distraction of the corrupt media that's trying to destroy the messenger, rather than cover the message of major corruption at the highest levels of our government.”

When he grew exasperated explaining his theories on Biden, Giuliani said: “Just read the newspaper.”