WASHINGTON -- The presidential race is on, full blast, and it's now clear this election will be a stark choice between two candidates with dramatically different visions of how to govern America.
The race could offer voters the starkest choice since 1964, said Dennis Goldford, a professor of politics at Drake University in Des Moines, Iowa.
That's when Republican conservative Barry Goldwater, with his message of leaner government and more personal responsibility, challenged President Lyndon Johnson and his Great Society -- and got trounced.
In 2012, Republican candidate Mitt Romney's choice of Rep. Paul Ryan as his running mate is a clear signal this race will be a fresh electoral test of ideology.
"You have two presidential candidates whose backgrounds are different, upbringings are different, philosophies and styles are different. Everything's different," said Sal Russo, a veteran Sacramento, Calif.-based Republican consultant.
Those differences will sharpen in the days and weeks ahead.
Republicans begin meeting Monday to draft a party platform, and there's little controversy over its contents: Government would shrink, tax rates would drop, and popular entitlement programs like Medicare would face broad changes.
Platform deliberations are expected to end Tuesday. The Republican convention begins Aug. 27 in Tampa, Fla., and Democrats start their gathering in Charlotte, N.C., eight days later.
Already, voters are getting a blunt taste of what's to come. Since Romney picked Ryan last weekend, the two sides have engaged in an increasingly tart war of words and ideas.
Democrats want to retain traditional Medicare; Republicans would offer seniors a choice of Medicare or private plans.
Democrats want to raise tax rates for the wealthy; Republicans would cut taxes by 20 percent across the board.
Republicans seek big domestic spending cuts; Democrats suggest a more gentle approach.
"What Romney is saying is that everyone should take care of themselves," said Bob Mulholland, a California Democratic consultant.
No, say Republicans. Our message is that government should provide opportunity and incentives, not guarantees.
"What Obama wants to do is grow the government," said Russo, "and that means more spending and more debt."
Obama allies counter that Romney wants to take money from Medicare and other programs "to pay for massive tax cuts for millionaires and billionaires -- the very same top-down economic scheme that crashed our economy and devastated the middle class in the first place," said Obama campaign spokeswoman Lis Smith.
Whether any of this August scuffling will matter when voters go to the polls in November is uncertain. The last times presidents sought re-election -- Bill Clinton in 1996 and George W. Bush in 2004 -- they spent the summer raising serious doubts about their opponents. Those doubts built momentum that lasted through the fall and helped bring victory to both. So far, Obama has been only mildly successful in hurting Romney.
The day before Romney picked Ryan, "Obama would have been elected if the election were held that day," said Peter Brown, assistant director of the Quinnipiac University poll.
Obama had opened up comfortable though hardly overwhelming leads nationally and in key battleground states, after a summer of painting Romney as an out-of-touch businessman whose refusal to release past tax returns seemed suspicious. Adding to Romney's woes was his July foreign trip, where his stumbles became daily headlines.
"The Obama people played this very well," said Tim Blessing, a professor of history and political science at Pennsylvania's Alvernia University.
But the president never seized enough of a lead to become a prohibitive favorite. Frank Newport, editor of the Gallup Poll, noted that neither candidate has been able to build, let alone retain, much of an edge.
Newport could not say with any precision why the numbers trickle up and down. Not even Ryan appears to have made much difference. But he at least gave Romney a jolt of energy.
"He's articulate, young and aggressive, and he's obviously competent," Brown said.
And as chairman of the House Budget Committee, the Wisconsin Republican helps press the point that Romney's chief mission is to revive a struggling economy.
Add to all of this a contest with an increasingly ugly tone, and the stage is set for a pointed and personal campaign that could remain in doubt until the end.
"It's been a close race," Newport said. "It's hard to tell what will happen. Both candidates are hanging in there around 46 percent."