If Republican candidate Mitt Romney wins the White House next week, historians will cite the debate in Denver, Colorado, earlier this month for providing the initial spark that revved up his campaign's engine and allowed him to surge ahead.

Indeed, in a race that's getting tighter by the minute, Romney just moved ahead in key battleground state Ohio this week in a Rasmussen poll after being tied with President Barack Obama the week prior. The former Massachusetts governor has also advanced in swing states Florida and Virginia and is inching closer and closer to the finish line.

Before the debates, however, the dynamic was much different.

Prior to that initial contest, Romney had been getting pummeled by White House attack ads and seemed unable to come back swinging. Campaign donors had begun to doubt his ability to ramp up his game, and some U.S. media reported that Romney's financial supporters were considering backing away from him.

Situation suddenly changed when Romney brought his A game to the first contest while the president brought his C game.

Obama seemed lackadaisical, at times testy, did not look at his opponent, and some pundits surmised that the president did not want to be there.

Key to that performance was that many Americans got their first up-close look at the challenger, who did not resemble the heartless capitalist portrayed in team Obama's myriad attack ads, analysts said.

Moreover, for a contender that has in the past had difficulty communicating with the public, debate watchers, pundits and U.S. media had no such impression that night. Romney was feisty and pulled no punches, but remained sincere and likable.

"The first debate was a game-changer because (Romney's) campaign was lacking heading into that debate," said Republican Strategist Ford O'Connell. "Now clearly he has the momentum on his side, but will it be enough to close the deal," that will remain unknown until the ballots are cast and counted, he added.

Two weeks later the two candidates faced off a second time in a town hall forum in which audience members asked the candidates questions. In desperate need of a comeback, the president came out swinging. But while Romney lost on points, at one point he stammered while discussing the September attack on the U.S. consulate in Benghazi, Libya, he was still able to pick up two points the next day in a Gallup daily tracking poll.

The third and final debate, which focused on foreign policy, surprised many, as Romney's strategy was to avoid casting himself as a warmonger in a war-weary nation, while presenting himself as a viable choice for commander-in-chief.

He agreed with Obama on a number of points, choosing not to be overly combative. He chose to let slide the controversy over the death of U.S. Ambassador to Libya Christopher Stevens and three other Americans, who were killed in an attack on the U.S. consulate on Sept. 11 in Benghazi. Again, he lost on points. But that did not seem to matter, because he continued to gain in the polls.

An upset would mark the third time in U.S. history that a presidential election's outcome is determined by debates, and the victory would serve as the final episode in a historical trilogy, the first chapter being in 1960 when former President John F. Kennedy beat Richard Nixon and the second in 2000 when the then Republican candidate George W. Bush won the debates against then Vice President Al Gore.