WASHINGTON It's show time for Barack Obama and John McCain, with back-to-back presidential nominating conventions offering them tightly-scripted spectacles designed to polish their images and highlight their messages.
The four-day Democratic and Republican conventions over the next two weeks will be a mix of pep rally and infomercial featuring carefully choreographed nightly programs that spotlight their life stories and campaign themes -- and what they see as their foe's weaknesses.
"The conventions provide a big national spotlight for both candidates, a chance to have the stage when voters are actually paying attention," said Democratic consultant Chris Kofinis, an aide to John Edwards during his 2008 presidential run.
"It is an incredible opportunity to tell the American people your vision for the country and what you will do as president -- and that can change the dynamics of the race," he said.
Obama kicks things off for Democrats in Denver on Monday and accepts the nomination with a prime-time, televised speech on Thursday, August 28. Republican McCain opens his convention four days later in St. Paul, Minnesota, and accepts the nomination on September 4.
It is unclear whether the back-to-back schedules will produce voter fatigue or offer an easy way to compare and contrast messages. For many voters, the conventions are the first time they tune into the general election race.
"It will be the showcase showdown," said Republican consultant Kevin Madden, an aide to Mitt Romney in his 2008 presidential campaign. "They are finished with just telling voters about themselves -- now they have to show voters they are ready to be president."
The conventions, along with looming vice presidential picks and head-to-head debates scheduled for late September and early October, are the biggest events on the calendar before McCain and Obama square off in a November 4 presidential election that polls show is tight.
The original purpose of national party conventions -- to choose White House candidates and adopt party positions on key issues -- has evolved into political theater in recent decades since the nominations are decided months in advance.
Both Obama and McCain hope their four days in the spotlight give them a measurable surge in opinion polls, known as "bounce." The Republicans could cut short any Obama surge by holding their convention so quickly after the Democrats.
The Democratic convention will feature a heavy dose of people who have shaped Obama's life and people he has met along the campaign trail in the past 18 months, with an emphasis on using the gathering to help organize a grass roots volunteer army, organizers said.
Obama will cap the gathering with his acceptance speech in Denver's 75,000-seat football stadium in what the campaign hopes is a momentum-generating climax.
But Democrats learned their lesson in 2004, when John Kerry earned no boost in the polls after a convention that focused on telling his own story and refrained from heavy attacks on President George W. Bush.
"There is definitely going to be a contrast drawn between the two candidates," said Jenny Backus, Obama's convention adviser. "This convention will make the choice crystal clear between two very different approaches to leadership."
Some Democrats said Obama, 47, a first-term Illinois senator, has more work to do spelling out specifically what his message of change means to the average voter.
"The real open question is what is he going to do? He has to take that question head-on in this convention and make it clear in an unequivocal way what the two or three priorities for his candidacy are," said Simon Rosenberg, head of the Democratic advocacy group NDN.
"I don't think Americans have a clear sense of what his plan for the American economy is. That is something they can fix at the convention, and they need to do that," he said.
Obama has tried to quell any uprising from the supporters of his vanquished primary rival New York Sen. Hillary Clinton, giving the former first lady and her husband, former President Bill Clinton, speaking roles at the convention and a chance to put her name in nomination.
McCain, a four-term Arizona senator and former Vietnam prisoner of war, will press his campaign-trail theme of drawing a sharp contrast between his record and what he calls the relative inexperience of Obama.
"Obama is cotton candy, it tastes great but you can't live on it. McCain is meat and potatoes," Madden said. "The convention will be an opportunity to offer that clear contrast."
With polls showing low approval ratings for Bush and many incumbent congressional Republicans in trouble, at least five Republican senators are skipping the gathering to focus on their own re-election bids.
Bush and Vice President Dick Cheney will speak on the opening night, and Democrats hope to make the most of their appearances.
"If McCain wants to distance himself from the Bush era, I don't think the convention will do that. It's going to undo some of the good work he has done in the last month," Rosenberg said.
(Editing by Alan Elsner)