WASHINGTON, D.C. — As Jimmy Kimmel once again urged viewers to call their senators and urge them to vote against the GOP’s latest plan to repeal and replace Obamacare, his late-night rival had a message for him on Twitter:

“Please @JimmyKimmel – stay out of politics. Leave the important stuff to reality TV stars with a knack for bankrupting casinos,” Stephen Colbert wrote.

It was a friendly word of solidarity as Kimmel has been dismissed as just a comedian with no business weighing in on the health care debate, or a member of the Hollywood elite unqualified to claim to know what is even in the Graham-Cassidy bill.

Kimmel didn’t shrink from the debate but instead pushed back against the criticism on Thursday, his third night in a row in which he has attacked the Republican health care plan and one of its key co-sponsors, Sen. Bill Cassidy (R-La.).

Unusual as it may be for Kimmel to take such an active role in trying to mobilize opposition to a pending piece of legislation, it is not entirely out of the ordinary for a late-night host to drop punch lines and veer into the center of a serious Capitol Hill policy fight.

Robert Lichter, author of “Politics Is a Joke! How TV Comedians Are Remaking Political Life,” points to Jon Stewart, who in 2010 devoted an entire show to pushing for a bill to fund assistance for first responders on 9/11, as it was being held up by Republican senators. Three years later, Stewart slammed the House GOP for voting against a bill to supply aid to victims of Hurricane Sandy. In 2013, David Letterman called out Republican senators for voting against gun control legislation.

Colbert testified at a House hearing on immigrant farm workers, and only briefly stepped out of his Comedy Central host persona, using sarcasm even when questioned by lawmakers. Some Republicans complained that he mocked the hearing process, but there was little doubt that he drew attention to an issue that otherwise would have gotten little.

With his CBS show, it’s now expected that Colbert, no longer in persona, will be politically biting, particularly toward President Donald Trump and those on the right.

Kimmel addressed health care in May after relaying the story of how his infant son had emergency heart surgery. That led him to talk of the need for less-well-off families to have affordable health care insurance, as well as protections for pre-existing conditions and restrictions on lifetime caps.

After Kimmel’s monologue spread virally, Cassidy referred to a “Kimmel test,” or that any legislation would have to guarantee affordable coverage for families. He then went on Kimmel’s show.

But this week, Kimmel attacked Cassidy, telling viewers that the senator lied to him about supporting a bill that offered those guarantees. Cassidy still insists that the bill will protect families in need of lower-cost insurance.

In his most recent monologue on Thursday, Kimmel went a step further: He urged viewers to call their senator, and flashed the phone number of the Capitol on screen. John Oliver has made similar pleas on his HBO series “Last Week Tonight,” urging viewers to contact the FCC to save net neutrality, while Bill Maher has used his HBO show “Real Time” to try to “flip a district” in 2014. (The Republican congressman he tried to oust, John Kline of Minnesota, was reelected.)

Lichter, professor of communication at George Mason University, said that Kimmel is “perhaps the least overtly political of all the major talk show hosts.”

“Kimmel has displayed his skill as grounding a policy preference in a touching personal anecdote that produces an emotional connection with his audience,” Lichter said. “Even more notable (and perhaps this is unprecedented) is his willingness to use his show as a platform for ongoing debate with critics and to call for direct action from the public. Who would have thought he’d be such a natural politician for our age of mediated politics?”

Kimmel is now linked to one of the most politically divisive of all issues, but the effort to defeat the Graham-Cassidy bill may be working. Sen. John McCain (R-Arizona) said on Friday that he would not support it, leaving Republicans without a key vote. It’s unclear whether Kimmel had anything at all to do with McCain’s decision, but he very quickly praised the Arizona senator for “being a hero again and again and now AGAIN.”