WASHINGTON -- Locked in a stubbornly tight race, President Barack Obama and Republican Mitt Romney are demonstrating the urgency of the campaign's final stretch, with the incumbent alone set to cover 5,300 miles in the busiest single day of his re-election bid. Both men claimed a growing edge even as voters showed little give.

From Colorado to Iowa to ever-important Ohio, bigger crowds and late October scenery offered the feel of a campaign starting to finally crackle. Obama centered on a closing theme that voters simply cannot trust Romney, while the challenger warned of the bleak times that four more Obama years would bring.

At the majestic Red Rocks Amphitheatre in Colorado late Tuesday, Romney said Obama's promise of more of the same is "why he's slipping and it's why we're gaining."

He cast the race as moving his way during a rally of up to 10,000 at the amphitheater, a stunning setting cut into mountain rocks outside Denver. Blue lights and the Romney "R'' logo lit the rocks rising on either side of the venue, and the crowd wore colored T-shirts that, viewed from afar, formed the Colorado state flag.

Romney wasn't staying in Colorado long. With just two weeks left and all three of their debates behind them, the candidates turned to travel - a lot of it.

Their mission remains to sway the small pool of undecided voters, but their increasing emphasis is to implore their millions of supporters to vote, particularly in the battleground states that allow early ballots to be cast.

Setting up for a frenetic finish, both campaigns sought to show they had enthusiasm and organization on their side.

"We have the ball, we have the lead," Obama campaign strategist David Axelrod insisted.

Obama was to campaign nearly around the clock Wednesday.

His day was taking him from Washington to Iowa, Colorado, California and Nevada, and then overnight to Florida. Not stopping to sleep in a hotel was meant to signal spirit and drive - although, with a comfortable suite on Air Force One, Obama was hardly crashing out in the coach section for his red-eye flight.

It was the first time Obama was spending the night on his plane for a domestic trip, but far from unprecedented for an incumbent scrambling to keep his job.

Across the miles, Obama was holding rallies from morning to night, appearing on "The Tonight Show" with Jay Leno and calling some voters from the plane. It is the first half of a two-day trip that will see him going to Florida, Virginia and Ohio on Thursday, with a stop sandwiched in for him to cast his vote in Chicago.

Romney, too, is picking up the pace.

He is campaigning Wednesday in Reno, Nev., and Cedar Rapids, Iowa, before a three-stop swing in Ohio on Thursday.

"His is a status quo candidacy," Romney said of Obama as he teamed with running mate Paul Ryan in Henderson, Nev., on Tuesday. Thousands gathered at Red Rocks to hear him, although the sound system made him sound distant.

A swell of public polling showed an up-for-grabs race.

The Obama campaign had clearly heard the complaint that Obama, after more than a year of speeches, had failed to articulate his second-term vision. Obama's team produced a 20-page booklet outlining his proposals and promised to distribute millions of copies. Obama himself held it up at two speeches.

In the closing phase, Obama is trying to capitalize on polls that show voters see the president as more trustworthy than Romney. The president has spiced his rhetoric with humor to temper his underlying charge - that Romney is lying about what he would do as president.

"We joke about Gov. Romney being all over the map, but it speaks to something important - it speaks of trust," Obama said in Dayton, Ohio. "Trust matters. You want to know that the person who's applying to be your president and commander in chief is trustworthy, that he means what he says."

With Obama holding an edge in the uncontested states, Romney must win more of the battlegrounds to reach the minimum 270 electoral votes for the presidency. Those states are Nevada, Colorado, Iowa, Wisconsin, Ohio, Virginia, North Carolina, Florida and New Hampshire.

All of them will be drawing enormous personal attention from Romney and Obama, their wives, their running mates and other surrogates through Nov. 6.

In those states, Romney and Obama have both focused on critical demographics - particularly female voters. Polls show more women backing Romney in recent weeks. But Romney could face some trouble over comments from Indiana Republican Senate candidate Richard Mourdock, who in a Tuesday night debate said that when a woman is impregnated during a rape, "it's something God intended."

Romney's campaign said late Tuesday that he "disagrees" with Mourdock but wouldn't say whether the campaign would ask him to stop airing a TV ad that Romney cut for Mourdock earlier this week.

Two months ago, embattled Missouri GOP Senate candidate Rep. Todd Akin said during a TV interview that women's bodies have ways of preventing pregnancy in cases of what he called "legitimate rape."

Since his comment, Akin has apologized repeatedly but has refused to leave the race despite calls to do so by leaders of his own party, including Romney.

From the Romney campaign, aides to Ryan were casting his speech Wednesday at Cleveland State University as a significant pitch.

He was to argue that Americans stuck in poverty cannot afford four more years like the past four. Ryan also planned to tell voters that Romney offers a better pathway for low-income Americans to improve their lives through opportunity and upward mobility, including school choice and public-private partnerships.