When Donald Trump appeared on “The Tonight Show Starring Jimmy Fallon” on Thursday, the show once again succeeded in getting a viral video moment: The host fussing with the Republican nominee’s hair.

But unlike Trump’s previous lighthearted appearances on the show, Fallon also is getting a lot of blowback for keeping his appearance lighthearted and not grilling the Republican nominee.

“In such a charged moment for the presidential campaign, Fallon had the opportunity to do something—anything—that could challenge the candidate,” wrote David Sims of The Atlantic. “He had hundreds of different issues he could have called Trump on. He decided to mess up his hair.”

Critics were more biting on Twitter.

It raises a question: Do late night talk show hosts, or daytime hosts, for that matter, have a responsibility to ask tough questions?

They are not journalists, but they are giving campaigns valuable exposure. In fact, it’s now a given that as part of their media schedule, candidates will turn to such “soft-talk” shows as a way to reach non-news audiences and boost their own likability.

Fallon, like other late-night hosts, has featured politicians and told political jokes. But unlike Stephen Colbert or Trevor Noah, he generally avoids the partisan thicket, just as Johnny Carson did in his day.

Fallon does not purport to be a probing interviewer. Rather, his show emphasizes comedy and laughs, and has been particularly successful in generating viral videos of celebrities and politicians that get wide traction the next day. Hillary Clinton, scheduled to appear on “The Tonight Show” on Monday, participated in a skit a year ago in which she spoke by phone to Fallon, playing Trump. It got more than 11 million views on YouTube.

The difference between then and now is that the stakes are higher, with just seven weeks to the general election. Candidate appearances, wherever they are, are subject to much more scrutiny. It’s as if the late night antics of a year ago are no longer just fun and games, but measured for their impact on the presidential race. Fallon’s critics pointed to the incongruity of yukking it up with Trump while not asking him about controversies about his foundation giving or birtherism.

“Don’t expect Jimmy Fallon to be Edward R. Murrow,” says Robert Lichter, director of the Center for Media and Public Affairs at George Mason University. “This is what Fallon does. He gives soft interviews to politicians, and they love it, whether it’s Barack Obama slow jamming the news or Donald Trump trying to sound presidential.”

He adds, “There’s a widespread feeling that Trump is getting away with murder on the campaign trail, and if only someone would expose him, his deluded supporters would drift away and the republic would be spared. So every public appearance he makes becomes a missed opportunity if the host doesn’t go for the jugular. But that isn’t the way politics works in this media environment.”

Trump is also unlike any other recent candidate and, as much as he has been a source of late night humor, he also presents a challenge.

In an interview with CNN’s Brian Lowry in June, Fallon’s predecessor Jay Leno suggested that Trump posed a different challenge than other politicians given his rhetoric.

“How do you play fair? How do you do a pro-Donald Trump joke? You can’t. At least with Bush or Clinton, you could go back and forth. But this….”

Asked how he’d treat Trump, Leno said, “I’m sure I’d be polite. I couldn’t see myself being overly gracious. I would try to nail him down and keep him from hitting all the stupid talking points. It’s just uncomfortable to watch.”

Daytime talk shows also have to reckon with the downside of featuring candidates. Trump’s appearance on “The Dr. Oz Show” came with criticism that the soft-talk daytime show was giving him a platform to trumpet the release of his medical records. In the days before the interview, Mehmet Oz said that he wouldn’t be engaging in a confrontational interview, and he ended up giving Trump his blessing that he was in fine health.

Likewise, there is bound to also be scrutiny when Tim Kaine, Hillary Clinton’s running mate, appears on “The Ellen DeGeneres Show” on Aug. 21. DeGeneres contributed $100,000 to the Hillary Victory Fund in April, according to the Federal Election Commission.

Should DeGeneres disclose her support next week? There are no legal requirements, and campaign finance watchers are mixed when it comes to the ethics of the question.

Sheila Krumholz, executive director of the Center for Responsive Politics, said via email that even though reporters would need disclose donations or gifts, “there’s no real ethical obligation for an entertainer like DeGeneres. I guess an argument could be made, and it certainly would be ideal from the standpoint of promoting transparency wherever politics comes into play. However, it seems pretty weak since she isn’t generally viewed as someone who holds herself out to be either a neutral observer or a political expert.”

Meredith McGehee, policy director of the campaign legal center, said that “there is no legal obligation for [DeGeneres] to disclose. That being said, she should.”

When DeGeneres interviewed Clinton in May, her enthusiasm for the Democratic candidate was pretty apparent. A watcher would probably not come away thinking DeGeneres had an affinity for Trump. She has said that he would be welcome to come on the show, which he has not done since announcing his candidacy. A spokeswoman for the show did not return requests for comment.

Other hosts have tried to avoid the situation altogether. After she endorsed Barack Obama’s 2008 presidential campaign, Oprah Winfrey decided not to “use my show as a platform for any of the candidates,” as she wrote back then. In previous cycles, she had invited the presidential candidates to appear on the show, and they eagerly accepted.

Lichter, who co-authored “Politics is a Joke! How TV Comedians Are Remaking Political Life,” suggests that there is another way of looking at talk shows’ penchant for soft interviews.

He notes that hosts like John Oliver and Colbert have “tried using humor to go after Trump, to no obvious effect.

“Maybe it’s not such a bad thing to permit a lighter moment in the midst of this dark presidential campaign.”