US Democratic presidential candidate Barack Obama has attacked his rival for negative campaigning as the election campaign enters its final 10 days.

Mr Obama, appearing in Nevada, said the "ugly phone calls, the misleading mail and TV ads, the careless, outrageous comments" were preventing change.

Republican rival John McCain, aware of being behind in the polls as he spoke in New Mexico, said he was a "fighter".

He told supporters not to give up hope of a White House victory.

Both candidates were campaigning in western US states during the weekend.

Nevada, New Mexico and Colorado were all Republican at the last election but could prove crucial if the vote is tight on 4 November.

Mr Obama, returning to the campaign trail after two days off in

which he flew to his ailing grandmother in Hawaii, said a negative campaign was not what the country needed.

"In the final days of campaigns, the say-anything, do-anything politics too often takes over. We've seen it before. And we're seeing it again today," he told a rally.

"Well, this isn't what we need right now.

"The American people don't want to hear politicians attack each other - you want to hear about how we're going to attack the challenges facing middle-class families each and every day."

John McCain at a rally in New Mexico
John McCain urged supporters not to give up hope

During his own rally in New Mexico, Mr McCain had attacked Mr Obama's tax policy as "re-distributing wealth" which would badly impact on the middle class.

Mr McCain told supporters to

"stand up and fight. America's worth fighting for."

With a poll for Newsweek putting him 13 percentage points behind Mr Obama, Mr McCain said: "I will never allow this nation to be defeated ... my friends, we've got them just where we want them.

"We love being the underdog and we're going to win! What America needs now is a fighter."

Attempting to distance himself from President George W Bush, Mr McCain said: "We cannot spend the next four years as we have much of the last eight, hoping for our luck to change at home and abroad."

While campaigning on Saturday in Sioux City, Iowa, Mr McCain's vice-presidential candidate Sarah Palin said her criticism of Obama had not been negative.

"Don't be made to feel guilty. I'm not feeling guilty," she said as calls of "he's a socialist" were heard from the crowd.