When US presidential candidates meet with wealthy campaign donors, one might not expect late-night talk shows to be a burning topic of discussion.
But during his now-infamous "47 percent" speech at a fundraiser in May, Republican challenger Mitt Romney also discussed popular talk show hosts Jay Leno and David Letterman-purveyors of the kind of late-night variety entertainment that has become serious business in US politics.
"I've been on Letterman a couple of times. I've been on Leno more than a couple of times," Romney told the donors. "And now Letterman hates me because I've been on Leno more than him."
Over the past two decades, appearances on late-night talk shows have become a staple of US presidential campaigns, offering candidates the chance to exchange banter with the hosts and display the humor and spontaneity often lacking from highly choreographed campaign events.
It's a trend that only seems to be gathering steam. US President Barack Obama last month made his seventh appearance on Letterman's show, and he has sat down for interviews with numerous others over the past several years.
The conversation is typically light but can often touch on serious issues.
During an interview Thursday with The Daily Show, host Jon Stewart pressed the president about his administration's contradictory versions about the deadly attack on a US embassy compound in Libya last month.
But Obama also joked with Daily Show host about how his vice president, Joe Biden, looks in a wet swimsuit.
Late-night talk shows provide an "opportunity to speak as directly as possible to the public and show who you are as a personality," said Chris Lehane, a former senior aide to President Bill Clinton and Democratic presidential candidate Al Gore.
These shows serve the same role that town squares or cross-country campaign train trips in bygone eras of presidential campaigns, Lehane added.
"It's like giving a speech from the back of the train or in the public square," he said.
Variety shows are not an exclusively modern phenomenon in American presidential politics.
Candidates John F. Kennedy and Richard Nixon appeared on The Tonight Show with Jack Paar in the summer of 1960, just months before Kennedy narrowly won the election.
Ronald Regan sat down with Johnny Carson in 1975 a few months before announcing his candidacy for the 1976 presidential election.
And Bill Clinton famously donned a pair of shades and played "Heartbreak Hotel" on his saxophone on The Arsenio Hall Show during the 1992 election.
But with a highly polarized electorate, campaigns have increasingly seen these programs as a way for their candidates to reach persuadable voters who don't follow every ebb and flow of the presidential race, said political scientist Stephen Farnsworth, an expert on media and politics.
"These are people who are not going to be moved by economic policy or by abortion," said Farnsworth, director of the Center for Leadership and Media Studies at Mary Washington University in Virginia. "They are going to be moved by how they feel about a candidate: Do they trust him? Do they like this person? That's what will make the difference."
Before sending its candidate on stage in front of a late-night studio audience, a presidential campaign typically engages in discussions with the show's producer to ensure they understand the arc of the program, said Lehane, a longtime Democratic operative.
"There's also a significant amount of time spent by the candidate and staff coming up with one-liners," Lehane said. "... The worst thing to do is to come on the program and come off as stiff. That's absolutely counterproductive."
Opting to forego late-night talk shows has its perils as well, Farnsworth said. Spurning an invitation to appear on a show can set a candidate up as the host's comedic punching bag.
Such appears to be the case with Letterman and Romney. Letterman has instructed his audience not to vote for the Republican candidate unless he comes on the show, and the comedian stepped up his rhetoric last week.
"You can't blow this off, Mitt," Letterman said during his October 10 show. "I'm telling you with every fiber of my being: If you want to go to the White House-not on the tour-you have to come here and shut me up. You've got to prove that I'm a dumbass punk, and you've got to come here and do it now. ... Because we wouldn't want anything to go the wrong way."
Lehane compared the late-night comedy circuit's role in US politics to that of Russian President Vladimir Putin's swashbuckling photo-ops in Russian politics, including Putin's staged discovery of two amphoras while diving with archeologists in the Black Sea last year.
"When we see President Obama diving for amphoras in the Great Lakes, then we will know that we have reached a true inflection point where the Russian analog to the late night comedy shows has crossed over to the US," Lehane said.