(CNN) -- In most presidential races this close, it is a battle for the undecideds and independents.
Pre-convention interviews with both Republican and Democratic delegates suggest this year might be more like trench warfare -- firing up the party faithful, starting in Tampa and Charlotte, to mobilize a high grassroots voter turnout in November.
"Conventional wisdom is that this election is about independents, but in reality it's about the base," said Orit Sklar, a Georgia-based longtime Romney activist attending her first convention as part of a state delegation.
"For Republicans, it means the convention is that much more important this time around. Our base has to be energized leaving Tampa, because we have to do everything we can not only to elect Mitt Romney, but to win the Senate and gain greater control of the House."
Like President Barack Obama, Philadelphia City Councilman Kenyatta Johnson launched his political career as an inner-city community activist. He says the mission is no different for Democrats.
"I'm a grassroots organizer at heart. ... You've got to make sure you get everyone at every level involved, all pushing the same message," he said.
"We want to make sure we go block by block, house by house, door by door, to make sure we get every vote possible."
That view is echoed by Georgia Democratic delegate Steve Henson, minority leader of the state Senate.
"You better be on your p's and q's on Election Day and make sure your people are coming," he said. "Turnout's a concern in every state for both parties. You've got to get your people to the polls."
Republicans liken this year's race to 1980 when the contrasts between the two candidates -- Ronald Reagan and then-President Jimmy Carter -- were just as stark.
But some analysts say the more apt comparison is 2004 when the incumbent, Republican George W. Bush, "was as much of a lightning rod as President Obama is today," as chief CNN pollster Keating Holland put it.
"This is not an election where you are trying to persuade independents," Holland said. "The selection of Paul Ryan is evidence of this. ... The Ryan pick was a base election strategy."
Ryan's selection was heartily applauded by Debbie Dooley, the Atlanta-based national coordinator of Tea Party Patriots.
"I didn't think Romney would be bold or courageous enough to pick Paul Ryan as his running mate," she said. "That signals the direction he's going in. He's not trying to run away from some of the statements Paul Ryan has made in regards to Medicare and some of the other issues."
Before Romney picked Ryan, some conservatives seemed to be more anti-Obama than pro-Romney. A similar situation existed in 2004, with Republicans occupying the White House.
"With all respect to John Kerry, the party was united against Bush," recalled Michigan Democratic Chairman Mark Brewer, who is going to his sixth convention, this time as a so-called "super-delegate." "He ran as a compassionate conservative in 2000. That went out the door with tax cuts for the rich and two wars he paid for with credit cards."
Kentucky GOP delegate Mark Metcalf is a U.S. Army reservist who served in Iraq after working in the Bush Justice Department and later at the Pentagon as associate deputy general counsel.
Metcalf went to his first convention in 1980, as chairman of Kentucky's Young Republicans and a supporter of dark horse presidential candidate Howard Baker, the senator from Tennessee who achieved fame by asking "What did the president know, and when did he know it?" during the Watergate scandal that brought down Richard Nixon.
"It was a convention I went to believing in a man who really didn't get very far in the presidential race, and I left as an advocate for Ronald Reagan," he says.
Of this year's contest, Metcalf says: "In my lifetime, I think this is probably the most important presidential election we've ever had. There's two very different visions of America offered by Governor Romney and President Obama. What's at stake is the free enterprise system as it has been articulated during the history of this country.
"President Obama stands for more government, less freedom and less personal responsibility. Governor Romney stands for free enterprise, less government, more freedom."
Two Democratic delegates from Florida stressed the importance of Obama's appeal to minorities and young people, voter blocs that were pivotal for him four years ago.
"I think the outcome of the election may very well be determined by the number of young people who come out to vote," said Stephanie Rosendorf, 21, director of political affairs for Florida College Democrats, a first-time voter herself in 2008.
"I think we can either choose to re-elect our president and continue to make progress or we can go back to the last decade and its failed policies."
Annette Taddeo, a Colombian-American small business owner, ran for Congress on the ticket with Obama in 2008 but lost to popular Cuban-born Rep. Ileana Ros-Lehtinen in south Florida.
A longtime party activist, she was cheered by Obama's decision to exempt from deportation children of illegal immigrants who pursue a college education, his endorsement of same-sex marriage and the party's proposed platform plank embracing that position.
Of Obama's runs for the presidency, Taddeo says, "The first time it was historic; this time it's personal because the attacks have been so personal -- frankly, below the belt -- throughout his presidency. It's unacceptable.
"Obamacare wasn't good enough even though it's the same as Romneycare just because it came from his mouth."
Dooley, who stresses fiscal conservatism over social issues, says tea party get-out-the-vote efforts are focused on Senate, congressional and local contests.
"If we get people out for those races, those people are going to vote for Romney," she says.
"We feel Georgia is a red state so the Tea Party Patriots and Atlanta Tea Party are sending people to Florida, maybe Virginia, some of the other battleground states, to help there."
Holland, the CNN pollster, says it all gets down to the grassroots.
"The Republican conventional wisdom is the Obama coalition from 2008 was a coalition of people who are known for not voting," he said. "So they believe if they motivate their base and Obama tries to mobilize his base, he will fall short."
Brewer, the Michigan Democratic chairman, disagrees with that scenario.
"I think there really is respect and affection for the president for all the things he's done under the circumstances," he said. "And then we look at the alternative -- Romney and the tea party Republicans and all the things they would roll back, overturn and repeal."