FORT COLLINS, Colo. — Barack Obama and John McCain began to ease back their attacks on one another yesterday, a sign that both presidential candidates will seek to end the long, bitter race on a positive note.

Obama, the Democratic nominee, drew more than 100,000 people to a rally in Denver, and another 45,000 to a rally in Fort Collins. "We have always been at our best when we're called to look past our differences and to come together as one nation, leadership that rallied this country to a common purpose, to a higher purpose," Obama told the Denver crowd.

McCain, the Republican nominee, stumped for votes before far smaller but enthusiastic audiences at three stops in rural Iowa and Ohio, states he calls "must-win" for his underdog campaign.

"I'm going to create wealth for all Americans by creating opportunity for all Americans," he said at a rally in Zanesville, Ohio.

Appearing earlier on NBC's "Meet the Press," McCain waved aside national polls that show him trailing far behind Obama, and insisted that he will stage an upset victory. He insisted the race has "closed" in the past week, and that he remains in striking distance.

"Obviously, I choose to trust my senses as well as the polls," the Arizona senator said. "I've been in a lot of presidential campaigns. I see the intensity out there. I see the passion. We're very competitive out there."

He added, "We're going to be up very, very late on election night."

But after a week of sagging polls and small crowds in nearly every battleground state, McCain found little apparent encouragement in Cedar Falls, Iowa, his first stop of the day.

The latest statewide poll showed Obama has widened his lead over McCain in Iowa to 15 points. And the state's largest newspaper, the Des Moines Register, endorsed Obama.

McCain's aides insist he remains upbeat and intently focused despite such setbacks. They say he campaigns best as the underdog, and will fight until the last vote is cast.

But the campaign has taken on what sometimes seems a plaintive tone. When Sen. Lindsey Graham, R-S.C., introduced McCain to 2,600 people at the University of Northern Iowa, he pleaded for support.

"We need you, we need you," he told the crowd. "John McCain needs your help. He deserves your help."

When McCain took the stage, he conceded that he was "a few points down." In a rare admission, he even mentioned a possible defeat on Nov. 4.

"I fought for you most of my life where defeat meant more than returning to the Senate," he said.

It was the 41st anniversary of the day McCain, then a Navy pilot, "intercepted a surface-to-air missile with my airplane," as he described it yesterday, over North Vietnam. He spent more than five years as a prisoner of war.

It is a sign of McCain's apparent plight now that he increasingly claims that, if for no other reason, voters should send him to the Oval Office to serve as a safeguard against a Democratic majority in Congress.

He peppers his speech with warnings about House Speaker Nancy Pelosi, D-Calif.; Senate Majority Leader Harry Reid, D-Nev.; and Rep. Barney Frank, D-Mass., who heads the House Financial Services Committee.

Obama is "making plans" with them to "raise taxes, increase spending and concede defeat in Iraq," McCain declared at a nighttime rally in Lancaster, Ohio.

Unlike the Democrats, he said, "we are not going to spread the wealth around." On foreign policy, he added, "I don't need any on-the-job training."

NO TAX INCREASES

In Colorado, Obama kept up his efforts to portray McCain as a virtual clone of President Bush, a charge the Republican staunchly denies.

"We know what the Bush-McCain philosophy looks like," the Illinois senator said in Fort Collins. "It's a philosophy that says we should give more and more to folks at the top, to millionaires and billionaires, to the wealthiest among us, and somehow it's going to trickle down to the rest of us."

Obama said a McCain White House would provide more tax breaks for wealthy individuals and corporations, while leaving middle-class families to bear the brunt of the faltering economy.

Obama touted his tax proposals, including giving tax credits to companies that create new jobs and offering a 90-day moratorium on home foreclosures to give struggling homeowners time to renegotiate their loans.

He also repeated his pledge not to increase taxes on families earning less than $250,000.

"Let me be crystal clear," he said. "If you make less than a quarter of a million dollars a year, which includes 98 percent of small-business owners and 99.9 percent of plumbers, then you won't see your taxes increase one single dime. Not your payroll tax, not your income tax, not your capital gains tax — no tax. That is my commitment to you."

SPENDING FREEZE

For his part, McCain vowed to cut business and capital gains taxes, and to freeze federal spending on all but essential programs such as defense, veterans affairs, Medicare and Medicaid.

But he also promised to build scores of nuclear power plants and "invest in all energy alternatives," including wind, solar, tide, natural gas and clean coal technology.

"I'm going to make government live on a budget, just like you do," he said in Zanesville.

In the TV interview, McCain disclosed for the first time that running mate Sarah Palin had "given back" one-third of the expensive clothes and accessories that the Republican National Committee bought her for public appearances.

News that the GOP spent $150,000 on her behalf at Neiman Marcus and Saks Fifth Avenue has tarnished Palin's image as a rough-hewn hockey mom who boasted last week in Ohio that she was proud to be called a "redneck woman."

A senior aide, Mark Salter, later explained that Palin returned "about a third" of the clothes because they were the wrong size or not her taste. McCain and his aides previously have said all the clothes would be donated to charity after the election.

McCain dismissed criticism of the expenditure and praised Palin.

"She lives a frugal life, she and her family are not wealthy, she and her family were thrust into this," he said. "She is a role model to millions and millions of Americans."

Seema Mehta reported from Fort Collins and Bob Drogin from Lancaster.