U.S. President Donald Trump remains silent after federal investigators’ question him, through writing and in person, regarding whether he attempted to block the probe into Russian interference during the 2016 election. Trump’s lawyer Rudy Giuliani told The Associated Press on Thursday that questions regarding obstruction of justice were a “no-go,” according to CNBC.

Giuliani provided the most conclusive rejection statement yet when special counsel Robert Mueller attempted to reach out to the president in an interview regarding any efforts to obstruct the investigation between his campaign and Russians. His defensive response gives insight that Trump’s lawyers are committed to protecting him from answering questions that may lead to bigger issues.

Giuliani’s public position remains unclear though, as Trump said he wants to answer questions under oath. Negotiations regarding the scope and format of conducting an interview are still ongoing and if the legal team continues to hold its stance, it could force Mueller to attempt to subpoena the president, which will likely trigger a standoff with the potential to lead to the Supreme Court.

Mueller’s office sought to interview the president in the past about the obstruction issue, including his firing of former FBI Director James Comey as well as his public attacks on Attorney General Jeff Sessions. Trump’s legal team argued back, stating the president holds power to hire and fire appointees. They also mentioned the special counsel doesn’t have the authority to ask him to explain those decisions made by Trump.

In a statement on Thursday, Giuliani said, “That’s a no-go. That is not going happen. There will be no questions at all on obstruction.”

Mueller’s team responded in a letter last week claiming it would accept written responses from Trump on questions related to Russian election interference. Giuliani implied Trump’s lawyers agreed to those terms but wanted to avoid follow-up questions from investigators.

“It would be in written form and if you want to follow up on our answers, justify it. Show us why you didn’t get there the first time,” Giuliani said. He said he isn’t categorically ruling out answering a second round of questions but is attempting to settle the matter of whether there is going to be follow-up inquiries. “We aren’t going to let them spring it on us,” said Giuliani.

Mueller’s office didn’t address obstruction questions in its latest letter to the legal team. According to a person familiar with the document, by withholding the obstruction questions, it indicates investigators would later assess what additional information is needed from the president after receiving answers to its initial questions.

The president publicly said he was eager to face questions from Mueller, but his lawyers remain far more reluctant to make him available for an interview. His team of lawyers still raise questions on whether Mueller holds the right to ask Trump about certain actions.

Trump and Giuliani led an onslaught of attacks on Mueller’s credibility including claiming the special counsel is biased and that the entire probe was a “witch hunt.” Giuliani went as far as demanding the probe suspends its activities with the midterm elections approaching, but the former mayor said he was not certain of Mueller’s intentions on Thursday.