Season finale? How debates have become the ultimate 'event' TV

It's been 26 days since the candidates left the stage at the last CNN debate in Jacksonville, Florida, and the growling hunger pangs of the media have grown louder even as the candidates grow weary.

There have been 19 Republican presidential debates so far, and while some may have debate fatigue -- including a few candidates -- the forums have nevertheless proved to be illuminating experiences. They have garnered sky-high TV ratings and have become "event" television. They have helped to define several candidates while others fall from grace in front of the live cameras.

But for many voters, it has been the debates -- especially those that have preceded a primary or caucuses -- that have become the deciding factor when they choose who they want as the GOP nominee. They have provided a window into each would-be nominee, and offered insights into how they act under pressure. According to exit polls, many voters make up their minds after watching a debate.

What has made the debates the fuel to feed the media's insatiable yearning for political fare? The storylines that have emerged have made the events essential viewing for political junkies and casual observers alike. Remember a fiery Newt Gingrich pushing back on marriage accusations, a tough Mitt Romney hitting Rick Santorum hard on social issues, a passionate Ron Paul pressing the Obama administration on foreign wars. Michele Bachmann and the HPV vaccine. And then there was Herman Cain and 9-9-9 ...

The debates return Wednesday night in Mesa, Ariz., as CNN partners with the Republican Party of Arizona to bring America the final debate before Super Tuesday, and what may be the final debate of the season.

Ahead of Wednesday's showdown, here's a recap of the last six major CNN debates, and what they could mean for this week's episode:

Manchester, N.H., June 13

Biggest storyline: Before Rick Perry had even entered the race, seven GOP candidates debated in the first offering to feature all major candidates. Rep. Michele Bachmann established herself as a major player, while former Gov. Tim Pawlenty gave a subdued performance, refusing to attack Mitt Romney.

Key moments: "Using the term 'Obamneycare' was a reflection of the president's comments that he designed Obamacare on the Massachusetts health care plan." -- Pawlenty.

"I filed today my paperwork to seek the office of the presidency of the United States today." -- Bachmann.

Post-debate fallout: Bachmann's strong performance started a surge that culminated with the Iowa straw poll victory. Pawlenty's weak showing started his spiral downward, ending with him dropping out of the race and endorsing Romney.

Tampa, Fla., Sept. 12

Biggest storyline: In a debate co-sponsored by elements of the tea party movement, Perry may have been the front-runner coming in, but he was hammered by Bachmann and Rick Santorum over the human papillomavirus vaccine.

Key moments: "To have innocent little 12-year-old girls to be forced to have government injections through an executive order is just flat-out wrong." -- Bachmann

Post-debate fallout: Perry's standing as the front-runner took an immediate and dramatic hit, with Romney taking over. Perry fell from 41 percent before the debate to 14 percent, with Romney moving from 28 percent to 51 percent.

Las Vegas, Oct. 18

Biggest storyline: Herman Cain's sudden surge to the front of the pack was set in stone as he hammered home the 9-9-9 plan. His rivals attacked.

Key moment: "The reason that our plan is being attacked so much is because lobbyists, accountants, politicians -- they don't want to throw out the current tax code and put in something that's simple and fair." -- Cain.

Post-debate fallout: Cain's surge came to an end, as far more scrutiny came to the 9-9-9 plan directly after the debate (as well as other, personal, issues). Also, the sparring between Romney and Rick Santorum was a sign of things to come between the two.

Washington, Nov. 22

Biggest storyline: A debate that focused on foreign policy saw Newt Gingrich open himself up to a potential problem over amnesty, while his rivals pounced. Meanwhile, Rep. Ron Paul established himself as the man on an island when it came to some major GOP issues.

Key moment: "I am prepared to take the heat for saying let's be humane in enforcing the law without giving them citizenship, but finding a way to give them legality so as not to separate them from their families." -- Gingrich. (He did.)

Post-debate fallout: Gingrich's surge continued, but rivals focused on this perceived weakness going forward. Meanwhile, Cain established a new nickname: "Blitz."

Charleston, S.C., Jan. 19

Biggest storyline: What may be one of the most memorable debate moments of the cycle occurred right off the top, with Gingrich attacking the media over claims made by his ex-wife. Santorum also took an opportunity to take on Gingrich over his "grandiose" ideas.