"The facts of global warming demand our urgent attention, especially in Washington," McCain told an audience at the Vestas Wind Technology plant in Portland, where he signed the blade of a giant wind turbine and chatted with service technicians.

Soon after taking taking office in 2001, Bush rejected the Kyoto Protocol that sets limits on industrial countries' greenhouse gas emissions.

The Republican president has resisted mandatory limits on greenhouse gas emissions, saying they would hurt the US economy.

'UNITED STATES WILL LEAD'

McCain's speech was aimed at independents and centrist Democrats whose votes he will need in the November election. His break with Bush comes as critics assert his candidacy amounts to little more than a third term for the current president.

"I will not shirk the mantle of leadership that the United States bears. I will not permit eight long years to pass without serious action on serious challenges," McCain said.

"I will not accept the same dead-end of failed diplomacy that claimed Kyoto."

On an issue that has complicated US relations with other countries, McCain said he would "lead and lead with a different approach -- an approach that speaks to the interests and obligations of every nation."

McCain said he would push for "meaningful environmental protocols," which included developing industrial powers India and China, to seek to cut worldwide greenhouse gas emissions.

He planned to present a so-called cap-and-trade system to Congress setting clear limits on greenhouse gas emissions for US businesses, while allowing the sale of rights to excess emissions, so as to "change the dynamic" of the US energy economy.

"Those who want clean coal technology, more wind and solar, nuclear power, biomass and biofuels will have their opportunity through a new market that rewards those and other innovations in clean energy," he said.

McCain said the plan would set out specific goals on US greenhouse gas emissions, including a return by 2012 to 2005 levels of emission, and by 2020 to 1990s levels.

His proposals drew fire from Democratic presidential front-runner Barack Obama, who faces off against rival Hillary Clinton in Oregon's Democratic primary on May 20.

"It is truly breathtaking for John McCain to talk about combating climate change while voting against virtually every recent effort to actually invest in clean energy," Obama said in a statement.

McCain has campaigned on his support for alternative energy sources including wind, solar and biomass technologies, as well as support for nuclear power, although Democrats question his voting record on the issue in Congress.