By day, White House hopefuls make speeches, meet voters and kiss babies. By night, they line up to trade jokes with America's late-night hosts - an increasingly important stop on the campaign trail.
Late-night talk shows - which are taped in the evening and broadcast just before midnight - are an institution in American television.
Traditional viewing audiences have waned, but are still in the millions - not too shabby for a presidential candidate looking to boost his or her profile before the primaries.
In the past 10 days, the parade of White House contenders from both parties who have appeared with the nation's kings of late-night comedy has been non-stop.
Viewers have seen Jeb Bush, whose Republican campaign is sputtering; Vice President Joe Biden, who cannot quite decide whether to run; Donald Trump, the billionaire Republican frontrunner, and Hillary Clinton, the Democratic frontrunner who is slipping in the polls.
The atmosphere is friendly and encourages humour, and the hosts generally tend to make a candidate look good. As public appearances go, it is pretty low-risk.
On Wednesday night, after Republican candidates did battle in their second debate, Clinton appeared on "The Tonight Show" with Jimmy Fallon, who dressed as Trump in one skit - a bit he unfurled with the real estate mogul himself a few nights before.
Candidates can poke fun at themselves and try to show a side of themselves that voters might not otherwise know about.
"It's a way to humanise a candidate," said Robert Thompson, a professor of television and popular culture at Syracuse University in New York state.
"You don't have to be a stand-up, you don't have to be telling a joke a minute. But you do have to be likable," Thompson said.
Cashing in on novelty, last week's debut of "The Late Show with Stephen Colbert" featured Bush and drew a good response with 6.6 million people watching.
But viewing habits are evolving. Fewer and fewer people watch the entire shows when they are aired, and fewer and fewer watch on an actual television.
Social media has changed the late-night game.
Thanks to the star quality of the current crop of hosts including Fallon, Colbert and Jimmy Kimmel, viewers don't have to stay up past midnight to catch the candidates.
"Just about everything now gets a second life in social media, but these shows in particular," said Robert Lichter, a professor of communications at George Mason University.
"You can fall asleep in front the TV while the show is on and yet hear all the great lines the next day on Twitter or Facebook."
In March 2009, Barack Obama became the first sitting president to appear on a late-night talk show. He has since appeared multiple times - memorably "slow-jamming" the news with Fallon - and always seemed to enjoy himself.
"Obama showed that going to these shows could be part of the presidency, not just part of presidential politics," said Lichter, predicting that Obama's successors will do the same.