Presidential debate fatigue: How many is too many?

Tonight in Tampa, Florida, the four men left in the Republican presidential nomination fight will gather for the 18th — yes, 18th! — time in the race to date.

CHARLESTON, SC - JANUARY 19: Republican presidential candidates (L-R) former U.S. Sen. Rick Santorum, former Massachusetts Gov. Mitt Romney, former Speaker of the House Newt Gingrich, and U.S. Rep. Ron Paul (R-TX) listen to a question from moderator John King (R) during a debate at the North Charleston Coliseum January 19, 2012 in Charleston, South Carolina. (Photo by John Moore/Getty Images)And tonight’s gathering, which will be carried live on NBC starting at 9 p.m. and live-blogged in this space too, is one of two two debates scheduled for this week. (The other, sponsored by CNN, is set for Thursday night.)

The frequency of debates has become a source of grumbling within some campaigns — cough, Mitt Romney, cough — but remains a ratings boon to the cable networks who host them. (CNN’s debate last Thursday drew 5 million viewers.)

And, they are clearly having influence on Republican voters. More than half (52 percent) of South Carolina primary voters said the recent debates were one of several important factors in deciding their vote. Of that group, Gingrich took 47 percent to 24 percent for Romney.

“There is never enough debates,” said R.C. Hammond, a spokesman for Gingrich. “Any candidate who toys with the idea of backing out of a GOP primary debate, you’d have to question how well they’d do on a debate stage with President Obama.”

(Romney briefly weighed skipping tonight’s debate before confirming his participation over the weekend; “There are too many of these,” Romney strategist Stuart Stevens said after last Monday’s debate. “We have to bring some order to it. We haven’t accepted Florida…It’s kind of like a cruise that’s gone on too long.” Stevens told the Post he was “thinking about setting myself on fire” from fatigue.)

So, have we reached a breaking point with debates? Or are they still a useful exercise for voters?

To answer that, it’s worth tracing the history of primary debates back a bit to find when we having two a week — or sometimes more — became the new normal.

That search leads up to the 2008 campaign when the first double open — no incumbent or sitting vice president running for office since 1952 — race coupled with huge national personalities like then Sens. Hillary Clinton, Barack Obama and John McCain not to mention former New York City Mayor Rudy Giuliani drew massive attention from even political passers-by.

In the 2008 Democratic primary, which, if you remember (and how could you forget!) went all the way until early June, featured 23 debates — 21 of which were televised. The slightly less high profile Republican presidential primary played host to 14 debates.

Add them up and you get almost 40 debates before either party had even picked their respective nominees.

David Karol, a professor at the University of Maryland who had studied the growth of presidential debates, notes that primary debates are nothing new — Tom Dewey debated (via radio) in the 1948 Republican primary while Adlai Stevenson debated with eventual running mate Estes Kefauver in the 1956 Democratic fight.

“That said, the process has changed in important ways,” said Karol. “Debates featuring a large group of candidate only became a routine part of the pre-nomination campaign in the 1980s. The number of debates has greatly increased since then and they now start much earlier in the cycle.”

Whether or not most people are sick of debates — and our anecdotal panel of one aka Mrs. Fix suggests some are — you can expect the number of them will only increase in frequency in 2016 and beyond.

For television networks, these debates have become must-watch programming, a sort of game of political “Survivor” played out in real time. And, as long as millions of people are watching them — and there’s no reason to think they won’t — networks will keep putting them on.

For candidates, the calculation going forward will likely be the same. While frontrunners like Romney will almost certainly push for less debate, the rest of the field will be heavily in favor of as many debates as possible — recognizing, rightly, that debates are the pebble that they have to sling at the Goliath frontrunners

Without debates, there is no Newt Gingrich surge — part 1 or part 2. And every underfunded, insurgent candidate will look to Gingrich’s example in 2016 and beyond.

If anything, there will likely be more debate in future presidential primary fights — not fewer.