By David Jackson, USA Today

When President Obama sits down Tuesday with Tonight show host Jay Leno, he'll be following -- and extending -- a trail blazed by many a politician.

Politicians have been trying to reach voters through late-night talk shows for more than 50 years, using techniques pioneered by candidates as different as Richard Nixon and Bill Clinton.

Obama's contribution: The first sitting president to do late-night television.

Tuesday is Obama's sixth appearance on The Tonight Show With Jay Leno, his fourth since moving into the White House.

As president, Obama has also made two appearances on Leno's rival program, The Late Show With David Letterman, as well as one with future Tonight show host Jimmy Fallon (with whom Obama "slow-jammed the news" about his student loan program).

Talk show politics played a role in one of the nation's most pivotal elections, the 1960 contest between John Kennedy and Richard Nixon. Both candidates appeared on the Tonight show, then hosted by Jack Paar.

It wasn't exactly hard-hitting stuff. During his interview of Kennedy, Paar asked, "Would it be rude of me if I called you John?" ("That would be fine," the future president replied.) But both nominees discussed election issues.

Though he lost that 1960 election, Nixon made an even bigger milestone appearance with Paar on March 8, 1963 -- two years and four months after losing the presidential election, four months after losing the 1962 California governor's race, and with John Kennedy in the White House and brother Robert Kennedy as attorney general.

When Paar asked, "Can Kennedy be defeated in '64?" Nixon deadpanned: "Which one?"

Paar then asked Nixon to play the piano, prompting Nixon to quip about his prospects for a future in politics: "If last November didn't finish it, this will."

Still, Nixon did play the piano. Five-and-a-half years later, he won the presidential election of 1968, capping a remarkable comeback that some historians trace back in part to his Tonight show appearance.

Nixon also provided lessons for politicians appearing on talk shows: Try to be at least amusing, and show a human side.

After Nixon, however, talk show presidential politics pretty much went into remission -- that is, until June 3, 1992.

On that seminal night, then-presumptive Democratic nominee Bill Clinton donned a pair of sunglasses, picked up a saxophone, and played Heartbreak Hotel on The Arsenio Hall Show.

At the time, Clinton was struggling in the polls against both incumbent President George H.W. Bush and independent billionaire candidate Ross Perot. The Arsenio gig helped Clinton re-introduce himself to a somewhat skeptical public.

That same year, Perot (as well as Clinton and incumbent President George H.W. Bush) sold themselves on prime-time cable talk show, Larry King Live.

As a result, talk shows -- all kinds of talk shows -- became standard features of presidential campaigns.

George W. Bush and John McCain, locked in a fierce battle for the Republican nomination in 2000, went on both Leno and Letterman during their primary battle.

Bush probably had a harder time. When Letterman asked the then-Texas governor, "How do you look so youthful and rested?" Bush said: "Fake it."

To which Letterman quickly shot back: "And that's pretty much how you're going to run the country?"

That fall, Bush and Democratic opponent Al Gore also did both Leno and Letterman shows.

By 2004, in seeking the Democratic nomination to oppose Bush, Howard Dean, John Edwards and John Kerry all did late-night talk shows.

When Obama and Hillary Rodham Clinton sought the Democratic presidential nomination in 2008, they both appeared on a different kind of late show, Saturday Night Live.

Obama and Clinton also expanded the political talk show universe, seeking to reach different audiences. Clinton went on The Daily Show, with its youthful demographics, while Obama sat down with the ladies of The View. Both candidates did The Colbert Report.

As for the more traditional venues, Obama made his first appearance with Leno back on Dec. 1, 2006, joking about his then-theoretical run for president.

When Leno said that "everybody who has announced here has been successful," Obama replied: "This is true, but I have to say that I've already committed to the Food Network to announce."

One Leno appearance in 2009 also illustrated the pitfalls of talk show appearances, the unintentional gaffe.

Obama joked that his bowling technique was "like the Special Olympics or something." He apologized to Special Olympics participants.