Washington (CNN) -- Mitt Romney waited until the presidential debates in the final five weeks of the election campaign to make his long-anticipated shift to the political center after previously espousing strongly conservative stances to win the Republican nomination.
The move appeared to catch President Barack Obama by surprise at their first face-to-face match up. His lackluster performance against a strong showing by Romney helped the former Massachusetts governor to catch, and in some places, pass the president in the polls.
Obama then fought back. He won the last two debates in the eyes of analysts and viewers with aggressive challenges to Romney's changing positions, framed by the president as a question of whether voters can trust his rival.
And some people say debates don't matter.
The roller-coaster ride of the 2012 campaign has been particularly volatile because of an unprecedented number of debates. There were more than 20 in the GOP primary campaign followed by the three presidential showdowns and one between the vice presidential contenders.
The multiple 90-minute sessions were almost all broadcast nationally on network or cable television. Voters were able to see an array of presidential hopefuls deal with the unique campaign pressure-cooker of differing styles, settings, moderators, audiences and issues -- all under the bright glare of stage lights and intense public scrutiny.
In the end, the debates likely did as much or more to shape public perceptions of the two final contenders than the billions of dollars spent on mostly negative advertising that have filled the airwaves nationally, particularly in the handful of battleground states still up for grabs and therefore crucial to winning the White House on November 6.
For Romney, the debates presented the last chance to fully introduce himself to a nationwide audience, and he waited until the first encounter in Denver on October 3 to make his strongest pitch for independent and moderate voters considered key to winning the election.
Romney could have started the shift a month earlier at the Republican National Convention in Tampa, but instead used his acceptance speech to focus on his personal qualities as a husband, father, local and regional Mormon church leader and successful businessman.
Rich Galen, a conservative commentator who formerly worked for former House Speaker Newt Gingrich, last week described a patient Romney strategy. The campaign waited until the home stretch to unveil a long-expected shift toward the middle by the candidate, who described himself as "severely conservative" during the primaries to try to appeal to the conservative base.
"They hold their fire, hold their fire, hold their fire, and then they sprint to the finish," Galen said, referring to what he called a "change in what he's saying and how he's saying it."
The shift "tells me that they had planned for a late-game surge," he said.
It appeared to work, with Romney's assertive debate performance in Denver providing traditionally Republican voters who questioned his presidential credentials with the validation they needed to support him.
Romney repeatedly invoked what he called the consequences of Obama's failed policies -- high unemployment, sluggish economic recovery, an onerous regulatory system that stifled growth -- with little challenge from the president.
He insisted his tax reforms to cut rates across the board and eliminate unspecified deductions would not increase the deficit, rejecting Obama's claim that it would.
At the same time, Romney also touted the health care reforms enacted in Massachusetts while he was governor, seeking to benefit from an issue that caused him trouble in the Republican primaries with conservatives who detest Obama's national health care reforms.
The Romney team "kind of reshaped his image at the debate to make him a more moderate figure," said Ron Brownstein, the National Journal editorial director and CNN senior political analyst, adding that it "would have been dangerous to do that earlier."
Romney "talked to the voters who are dissatisfied with Obama and reminded them why they were was dissatisfied and helped cross the threshold on why he would do better," while Obama "did nothing to frame the case against Romney" or explain what he would do in a second term to make things better, Brownstein said.
Until the first debate, he explained, Obama benefited from "a slice of the electorate who were clearly dissatisfied with his first term, were not sure he deserved a second term, but weren't sure if Romney was a viable alternative," thereby providing the president some margin of comfort.
"I think that permanently changed at the first debate," Brownstein said.
An immediate CNN/ORC International poll showed more than 60% of respondents who watched the Denver debate considered Romney the winner. In following weeks, Romney's poll numbers rose steadily, bringing him even with Obama in an aggregate of major national surveys and moving in front in key battleground states such as Florida and North Carolina.
With less than a month to go in the campaign, the Romney rise presented a potentially unstoppable problem for Obama. In response, the president adopted a more aggressive posture in the second and third debates. It focused on Romney's political shifts following his days leading moderate Massachusetts to his effort to win conservative support in the GOP primary, and then his latest move back toward the political center.
At Monday night's third and final debate in Florida, which highlighted foreign policy issues, Romney shifted or modified previous positions to agree with Obama on how to respond to the Syrian conflict and when to pull combat troops out of Afghanistan.
He also supported Obama's decision to take out al Qaeda leader Osama bin Laden, and to expand the use of drones to go after terrorist targets in Afghanistan and Pakistan. But Romney also sought to present himself as a reasonable -- and possibly more reasonable -- alternative to the president.
"We can't kill our way out of this mess," Romney said of combating terrorism, and he pushed for "a comprehensive strategy" to curb violent extremism in the Middle East.
"The key that we're going to have to pursue is a -- is a pathway to get the Muslim world to be able to reject extremism on its own," Romney said, proposing U.S. policies to promote economic development, better education, gender equity and to help create institutions.
However, he was unable to express any significant policy difference with Obama on how that would happen.
Obama responded by criticizing his opponent for proposing "wrong and reckless leadership that is all over the map," and analysts described Romney's positions as attacking Obama from the left, rather than the right.
Fareed Zakaria of CNN and Time magazine joked that Romney's stance invoked the spirit of anti-war Democratic presidential candidate George McGovern, who died over the weekend.
Meanwhile, Republican strategists said Romney achieved his goal of coming off as presidential, an assertion backed by the CNN/ORC poll that showed both candidates got high marks from respondents for leadership ability. Former White House Press Secretary Ari Fleischer, a Republican strategist and CNN contributor, said that was very important.
He noted that 24% of those questioned said the debate made them more likely to vote for Obama while 25% said it nudged them toward Romney, and 50% said they were not influence either way.
"This isn't going to change the trajectory of the result," Fleischer said.
The poll also reinforced a gender gap in the race, with women favoring Obama as a strong leader by 59% to 39%, while men chose Romney by 53% to 43%. Obama needs to repeat the strong support from women voters -- who comprise half the electorate -- that helped him win in 2008.
Obama continued his criticism of Romney at a campaign event Tuesday in the Sunshine State, a major battleground where Romney has a slight edge, according to the latest polls.
"We are accustomed to seeing politicians change their positions from like four years ago," Obama said. "We are not accustomed to seeing politicians change their positions from four days ago."
It comes down to trust, he continued, adding that "the person who leads this country, you have got to have confidence that he or she means what he or she says."
The Romney campaign called such criticism the hallmark of an incumbent who knows he is losing.
"While the Obama campaign continues to engage in desperate attacks, Gov. Romney will continue talking about his plan for a real recovery for the middle class, which has suffered under the failed Obama policies of the last four years," said a statement by Rich Beeson, Romney's political director.
In the Republican primaries, Romney came under strong attack from conservative challengers, including Gingrich, former Pennsylvania Sen. Rick Santorum, Texas Gov. Rick Perry and Minnesota Rep. Michele Bachmann, for being too moderate too face Obama.
Santorum said Romney's health care law in Massachusetts made him incapable of challenging Obama on the federal law opposed by conservatives, while Gingrich sounded criticism similar to what Obama says now in accusing Romney of changing positions for political reasons.
Romney managed to successfully navigate the primary minefield by alternating between aggressive attacks on his foes. For example, he accused Perry of being soft on illegal immigration, and at times trying to remain above the arguing between his rivals as they took turns in leading the field and becoming the main focus of criticism from the others.
The GOP debates included memorable meltdowns and other moments that narrowed the field, such as when Perry couldn't remember the name of one of three government departments he pledged to cut. Romney emerged as the survivor, but rarely won more than 50% of the vote in any of the primaries until his nomination was certain.
In the presidential debates, Romney's strong start changed the equation of the race and sparked a revitalized response from Obama. Post-debate polls showed respondents thought Obama won both of the final two encounters.
Now the question is whether the president's stronger performance translates to any bump in support, or at least slows or halts Romney's recent gains.
It all shows that debates do matter, and never more so than in this election cycle.