Democrat Michael Dukakis lashed at front-running George Bush as man with "no convictions, no ideas and no plans" yesterday and blamed Republican policies for last year's stock market plunge. Bush tried to contain supporters' enthusiasm over polls showing him building a large lead.

"We're not going to lighten up," the Republican presidential nominee said while campaigning in Missouri. "No votes can be taken for granted and I'm not taking any votes for granted. I will continue to campaign as an underdog."

There was no question who was the real underdog--Dukakis. But he drew enthusiastic crowds as he campaigned through Michigan with aides battling the growing perception that Bush had taken an insurmountable lead with just three weeks until the election.

Dukakis' running mate Lloyd Bentsen delivered a strongly worded response to the Republicans, accusing Bush of running "one of the most outrageous displays of negative campaigning ever seen in the history of national politics."

The Massachusetts governor sharpened his language as he focused on economic issues and portrayed Bush as the candidate of the wealthy.

"George Bush cares about he people on Easy Street," Dukakis said. "I care about the people on Main Street. He's on their side. I'm on your side."

"Duke, Duke, Duke," chanted the crowds.

Dukakis also brought up the huge stock-market drop that occurred one year ago today.

"The trade deficit had soared," he said. "Republican policies of borrow and spend and borrow and spend had done the damage."

He pledged to eliminate the $150 billion trade deficit in four years by reducing the budget deficit, increasing foreign trade, investing in education and putting more emphasis on research. He said Bush wouldn't talk about his plans.

"He's got the flags and balloons, but no convictions, no ideas and no plans," Dukakis said.

The Democrat's aides disputed an NBC-Wall Street Journal poll showing Bush with a 17-point lead, his largest of the campaign. They pointed instead to other polls indicating about half that margin.

Bush, trying to avoid overconfidence, campaigned in Fulton, Mo., and invoked the memory of Winston Churchill at the Westminster College where Churchill delivered his 1946 "iron curtain" speech warning of Soviet expansionism in Eastern Europe.

Bush said the demarcation between East and West is now "a rusting curtain." He said that if elected he would be wary of Soviet intentions, despite what he called more enlightened leadership under Mikhail Gorbachev.

"Now is not the time to abandon realism about what moves the Soviet Union," Bush said.