US Democratic presidential candidate Barack Obama has accused his Republican rival John McCain of negative campaigning 10 days before polling day.
Mr Obama, appearing in Nevada, said the "ugly phone calls, the misleading mail and TV ads, the careless, outrageous comments" were preventing "change".
Mr McCain accused Mr Obama in New Mexico of starting a victory lap before winning the election.
The two men are focusing on vital states in the west of the country.
Nevada, New Mexico and Colorado were all Republican at the last election but could prove crucial if the vote is tight on 4 November.
All the main national opinion polls suggest Barack Obama has a strong lead.
'Batman and Robin'
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..." he said in Las Vegas, Nevada.
"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."
Both Mr McCain and Mr Obama appeared in Albuquerque on Saturday
Later, in Albuquerque, New Mexico, he sought to tie Mr McCain to the policies of the outgoing Republican President, George W Bush.
"John McCain's mad at George Bush, so opposed to George Bush's policies, that he voted with him 90% of the time for the past eight years," he told a mass rally.
"That's right, he decided to really stick it to George Bush 10% of the time... It's like Robin getting mad at Batman."
Speaking in Mesilla, New Mexico, John McCain seized on a report in the New York Times that the Obama camp had already drafted an inaugural address for the Democrat - an allegation the campaign has rejected as "completely false".
"Senator Obama's inaugural address is already written," Mr McCain said. "I'm not making it up. A lot of voters are undecided but he's decided for them."
"What America needs now is someone who will finish the race before starting the victory lap," the Republican hopeful added.
Speaking earlier in Albuquerque, and with a Newsweek poll putting him 13 points behind Mr Obama, Mr McCain said he was happy to be the "underdog" of the election race and was going to win because "what America needs now is a fighter".
Attempting to distance himself from President Bush, he added: "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.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.