KANSAS CITY, Mo. - On a day when he set out to woo back Green-leaning voters, Al Gore trumpeted his environmental record and mentioned a dire report on global warming, saying that rival George W. Bush won't move fast enough on the problem.

Meanwhile, Bush said the Clinton-Gore administration has made little progress in eight years, engaging in a ''fruitless search for a legacy.''

In a campaign stop Thursday, Gore called global warming ''a moral issue'' after a United Nations-sponsored panel of scientists concluded that man-made pollution has ''contributed substantially'' to global warming. The study said the Earth is likely to get a lot hotter than previously predicted.

Bush ''has said that he's not convinced that the pollution is causing it, and that he's not convinced we should do anything other than just study it and I disagree with that,'' Gore said during a breakfast chat with blue collar workers at Kansas City's Town Topic diner.

''Some people want to dig in their heels and give over the policy to the big oil companies,'' Gore said.

In a conference call with reporters, U.S. Sen. John Kerry, D-Mass., criticized Bush for failing to ''accept the reality'' of the report, saying the reaction of the two candidates shows their differences on global warming.

''You have the individual who has been the single clearest and the most forceful leader on the subject of climate change ... versus an individual who has a state that has failed to live up to high standards and who himself doubts the scientific realities,'' he said.

Bush spokesman Dan Bartlett responded: ''The governor does believe it's a problem but also believes we should have all the best science and knowledge available before we make a decision.'' Still, Bartlett noted that Bush signed legislation as Texas governor requiring emissions reductions from utility plants exempted from the 1972 Clean Air Act.

Gore is also challenging voters to check out his environmental record, saying he can stand toe-to-toe with Ralph Nader.

With Bush-Gore horse race polls seesawing by just a couple of percentage points, Democrats are more and more anxious that Nader's single-digit support from independents and environmentalists could tip the race to Bush.

Democrat Gore already has touched down this week in two other states where Nader has support Washington state and Oregon and planned to campaign in Wisconsin and Minnesota. His Minnesota campaign chairman, Rick Stafford, stated Gore's message to Nader voters directly: ''Come back home.''

Gore was pushing through four states Thursday and Bush through two as each focused on the image problems Gore's personality and Bush's inexperience that pollster Andrew Kohut blamed for the deadlock in national polls.

In remarks prepared for a speech at the Soldiers and Sailors Museum in Pittsburgh, Bush slammed Gore and President Clinton for leaving only ''faint footprints, marking time, not making progress'' and being guided mostly by polls during eight years in the White House.

''They are going out as they came in: Their guide, the nightly polls. Their goal, the morning headlines. Their legacy, the fruitless search for a legacy,'' Bush said.

He invoked the shadow of impeachment, during which Clinton insisted that his answers under oath were legally sound if not completely truthful. ''In my administration, we will ask not only what is legal, but what is right not just what the lawyers allow, but what the public deserves,'' Bush said.

He also took a shot at Gore and his famous answer to questions about campaign fund raising.

''In my administration, we will make it clear there is the controlling authority of conscience,'' Bush said. ''We will make people proud again so that Americans who love their country can once again respect their government.''

Retired Gen. Colin Powell, popular among moderates, was joining forces with Bush in Pennsylvania under the banner ''Responsible Leadership.'' Bush aides counted on Powell to reinforce the message that Sen. John McCain carried as he campaigned with Bush on Wednesday: Bush ''is fully prepared to assume the duties of president of the United States.''

Gore also hoped to reach young voters and showcase his more personable side by taking questions at Scott Community College in Bettendorf, Iowa, during a taped appearance on rap star Queen Latifah's nationally syndicated TV talk show.

At Kansas City's Town Topic diner here, Gore had to work to get the chatter flowing. ''What were you talking about,'' he asked the morning crew, hoping to chew over campaign issues.

''Your rally last night,'' answered one worker.

Gore tried again: ''What else have y'all been talking about?''

''You being here,'' said another.

The latest survey by Kohut's Pew Research Center for the People & the Press found that almost a fourth of the nation's voters are ''swing voters,'' meaning they are only loosely committed and could still change their minds.

Asked if he would like Nader to drop out and endorse him, Gore laughed and said, ''I'd like for Bush to do that.''

Gore now is clearly looking over his shoulder at the consumer advocate and has added some Nader-style rhetoric to his stump speech.

''We've got a crazy campaign finance system that gives (insurance companies and HMOs) so much influence they just drown out the voice of the American people. We need to change that,'' Gore boomed at a Kansas City rally Wednesday night.