FCC Chairman Ajit Pai, appearing before a congressional oversight hearing, defended his response to President Donald Trump’s suggestion that the agency should look into revoking NBC’s license because of the way it has covered his administration.

Pai has declined to address Trump’s tweets directly, other than to say that he is a defender of the First Amendment and that the FCC lacked authority to revoke a license based on newscast content.

At Wednesday’s hearing, where he faced a number of Democrats critical that he did not immediately react to Trump’s tweets earlier this month and directly challenge him, Pai pointed to a past exchange between President John F. Kennedy and his then-FCC chairman, Newton Minow.

In an op-ed that ran in the Chicago Tribune late last year, Minow wrote that in one incident, Kennedy was so frustrated by the reporting on an NBC newscast that he called him up, furious, and said, “Did you see how those guys lied about me? Outrageous! Do something about it!”

“After careful reflection, I decided the best course was to do nothing,” Minow wrote.

A week later, Minow saw Kennedy at a diplomatic reception, and Kennedy “put his arm around me and whispered, ‘Thank you!'”

Minow, now 91 and one of the last living senior officials from the Kennedy administration, met with Pai last week.

By contrast, Trump’s attacks on NBC came in the form of public Twitter pronouncements. On Oct. 11, Trump made several Twitter attacks on NBC News, writing on one, “With all of the Fake News coming out of NBC and the Networks, at what point is it appropriate to challenge their License? Bad for country!”

Speaking to reporters on Tuesday, Pai said that he has not talked to the White House since then. He also suggested that the focus on his response was politically motivated. “I understand that those who oppose my agenda would like to be distracted by the controversy of the day.”

But some House Democrats criticized Pai for not responding until six days after Trump’s tweets. Some First Amendment groups characterized Trump’s comments as alarming attacks on the press. Rep. Anna Eshoo (D-Calif.) objected to the comparison of Trump with Kennedy. “To bring together President Kennedy with Donald Trump, I don’t believe is palatable, and I am just going to leave it there,” she said.

Rep. Mike Doyle (D-Pa.) said that he was “deeply alarmed” by Pai’s response.

“You took six days to respond to the president’s tweet, and when you did, you did not directly address the president’s threat at all, or its effects on the media,” Doyle said.

In pointing out past incidents that raised First Amendment concerns, Pai also cited an effort by the FCC led by his predecessor, Tom Wheeler, to conduct a “critical information needs” study. Pai called it “an ill-conceived initiative would have involved sending government-funded agents into newsrooms to second guess editorial judgment.” Pai wrote an op-ed blasting the study in 2014, and the agency abandoned it.

Commissioner Mignon Clyburn, however, took issue with the way that the study was characterized, and said that it was a study of the “entire media ecosystem,” and that the agency has suffered for it. “We are making decisions by putting our finger up in the wind and seeing where the political winds are flowing,” she said.

Pai also took aim at some of the Democrats who still sit on the committee, citing an effort to launch an investigation of a broadcaster based “solely on the content of a documentary that they didn’t like and that hadn’t even aired.” He was referring to Democrats’ calls in 2004 to investigate Sinclair Broadcast Group over their plans to air an anti-John Kerry Swift Boat documentary on their stations in the days before the election. They cited potential violations of equal time rules.

Sinclair is again a target as it seeks to merger with Tribune Media, creating the largest station group in the country with more than 200 outlets and covering 72% of the country. Public interest groups have attacked the merger — now pending before the FCC — as damaging to local programming. Some critics have cited conservative editorials that run across Sinclair station newscasts.

Pai has defended the FCC’s review of the merger. But at the hearing, Commissioner Jessica Rosenworcel said that she was “concerned” over the timing of decisions.

“If you look at the series of media policy decisions that have been made by this commission, they all seem to serve Sinclair Broadcasting’s business plans,” she said.

She added, “I think it has reached a point where all of our media policy decisions seem to be custom built for this one company, and it is something that merits investigation.”