It would be "a mistake" for special counsel Robert Mueller not to get in-person testimony from President Donald Trump, House Intelligence Chairman Adam Schiff, D-Calif., said Sunday on NBC's "Meet the Press."

"I think it is a mistake," Schiff said when asked by anchor Chuck Todd whether Mueller would err by deciding not to interview the president before a grand jury given the public testimony of others, such as Trump's former lawyer, Michael Cohen. "And I've said all along that I don't think Bob Mueller should rely on written answers. When you get written answers from a witness, it's really the lawyers' answers as much as the client's answer. And here you need to be able to ask follow-up questions in real time."

In November, Trump's legal team submitted written answers to Mueller's questions about Russian interference in the 2016 presidential election and whether Trump's campaign colluded in that effort. They did not answer questions regarding possible obstruction of justice related to the Russia probe.

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Trump's attorney, Rudy Giuliani, said in December that the president and his legal team would not provide Mueller with additional answers.

The submission of written answers followed months of back-and-forth between Trump's attorneys and Mueller's team about just what exactly the president would respond to and how he would provide those responses. In August, Trump's lawyers were already preparing a memo opposing a potential subpoena from Mueller to provide an in-person interview.

Responding to Schiff’s remarks, Giuliani accused Schiff in a text message to NBC News of coaching Cohen through his congressional testimony and questioned why Schiff would question the special counsel’s decision making.

"Since when did Schiff become the Special Counsel?" Giuliani said. "I thought he trusted Mueller. It only tells you Schiff wants to hurt the President no matter what. Also ask him how his staff spent 12 hours with Cohen to prepare his testimony and Cohen committed 4 to 6 demonstrable lies (perjury) during his testimony."

If Mueller were to file that subpoena only to be met with resistance from Trump's side, it could set off a monumental legal fight in federal court, possibly going all the way to the Supreme Court.

Schiff said he believes Mueller was constrained by then-acting Attorney General Matthew Whitaker, who Schiff said "was appointed because he would be hostile to a subpoena on the president."

Whitaker, who is no longer at the Department of Justice, has since been replaced by Attorney General William Barr, who Schiff said "was chosen for the same hostility to his investigation, who would likely oppose that step."

"I also think that the special counsel feels some time pressure to conclude his work," Schiff said. "And knowing that the White House would drag out a fight over the subpoena, that may be an issue as well."

"But I do think ultimately it's a mistake because probably the best way to get the truth would be to put the president under oath," Schiff continued. "Because as he's made plain in the past, he feels it's perfectly fine to lie to the public. After all, he has said, 'It's not like I'm talking before a magistrate.' Well, maybe he should talk before a magistrate."