Although President Obama experienced a modest post-convention public opinion “bounce,” neither the president nor former Massachusetts Gov. Mitt Romney delivered a breakthrough performance at their nominating parties.

In fact, both candidates were largely over-shadowed by more dynamic surrogates, notably first lady Michelle Obama, former President Bill Clinton and Florida Sen. Marco Rubio.

As a result, the fundamentals of the presidential race remain unchanged. It continues to be a close, bitter contest that will turn on either campaign’s ability to turn out their bases and convince the tiniest sliver of undecided voters in 10 or fewer battleground states to vote their way.

Given the persistent rigidity of the contest, the one vice presidential and three presidential debates take on even greater importance, providing the candidates with their last remaining opportunity to change the trajectory of the election with a dominating overall performance or even a single piercing rejoinder.

The debates play a pivotal role in defining or reinforcing a candidate’s character and creating historic election moments, when campaigns rise or fall. That’s largely because they present voters with their single greatest opportunity to see and hear from these candidates in an environment that actually encourages spontaneity and authenticity.

Think of President Ford’s absurd claim in 1976 that “there is no Soviet domination of Eastern Europe”; Ronald Reagan’s 1980 exhortation that “I am paying for this microphone”; Michael Dukakis’ stoic 1988 response to whether he would support the death penalty if his wife, Kitty, were raped and murdered; George H. W. Bush’s botched answer to a question about the national debt in 1992 as compared to Bill Clinton’s deeply personal and empathetic response; Lloyd Bentsen’s shattering “Senator, you’re no Jack Kennedy” assessment of Dan Quayle in 1998; Al Gore’s petulant, audible sighing in 2000; or even Gov. Rick Perry’s “oops” moment in the GOP primary debate last November.

Because the debates encourage these extemporaneous exchanges, they stand in stark contrast to campaigns that struggle mightily to keep candidates “on message” and organic, unscripted moments at bay. Poll-tested ads, carefully parsed speeches, and even media interviews with pre-approved ground rules now pass as “campaigning,” greatly limiting any opportunity for authentic moments.

That’s not to suggest the candidates won’t make every possible effort to stay on message during the debates. Quite the contrary. Each candidate will engage in hours of rigorous preparation to deliver messages specifically designed to sway the small universe of undecided voters in battleground states.

But Obama and Romney must do more than deliver well packaged sound bites. They must connect with voters on an emotional level, demonstrating that they understand the needs, cares and concerns of everyday Americans. Voters will ask themselves, “Does he understand the challenges in my life? Can he relate to me? What will he do to improve my circumstances?”

Whether the “cool on the outside” president or the urbane former governor can deliver an authentic, enduring “I feel your pain” moment is an open question.

That’s one reason the moderators of all three debates will attempt to push the candidates beyond their talking points, challenging previous statements and pressing for policy details. If they are able to engage the candidates in an authentic dialogue about their widely divergent policy prescriptions for America, it will elevate a campaign season too often mired in the trivial.

Even as the candidates debate on stage, their every move and utterance will be dissected in real time by pundits and reporters, as well as spun by the campaigns, each all too eager to declare a “winner” and “loser.”

The punditocracy’s instant analyses can be harsh and enduring, shaping future story lines and creating durable new campaign memes even before the candidates walk off stage.

During the primary, Romney proved a practiced and steady performer in 21 debates. However, those multi-candidate forums will seem quaint by comparison to the glare of going mano-a-mano with a sitting president. The stakes are infinitely higher.

In 2008, Obama outperformed Sen. John McCain and, in 2012, remains the better liked, more approachable and less gaffe-prone candidate.

By a slim margin, I give the debate advantage to Obama. Who wants to make a $10,000 bet?

Michael Cuzzi, a former campaign aide to President Obama, Sen. John Kerry and U.S. Rep. Tom Allen, manages the Portland office of VOX Global, a strategic communications and public affairs firm. He can be contacted at:

[email protected]

Twitter: @CuzziMJ.