Republican George Bush charged that rival Michael Dukakis is leading Massachusetts into a "budgetary Three Mile Island." The Democratic nominee, initially reluctant to join the rhetorical fray, defended his state's economy as sound.

The vice president, wrapping up a two-day campaign swing in California Thursday, also expressed his hope that former White House aide Oliver North will be exonerated on all federal charges stemming from his role in the Iran-Contra affair.Bush refused to rule out a presidential pardon if North, who is awaiting trial, is found guilty.

On economics, the Republican presidential nominee lashed out at his opponent, saying the Democratic governor's policies have hurt Massachussetts and will harm the nation.

Questioned about Bush's charges, a reticent Dukakis told reporters joining him on a tour of fire-ravaged Yellowstone National Park that he would reserve comment until "sometime next week."

But later, the Democratic nominee chose to respond to the attacks, and cited his state's low unemployment rate - 3 percent - and 10 straight balanced budgets.

Upon arriving in Los Angeles, Dukakis again, without prompting, told reporters, "What Mr. Bush has given us is a mountain of debt, record deficits, a record trade deficit and an economic future that does not bode well for the American people."

Dukakis was campaigning in Southern California Friday, stressing the fight against drugs and crime. The Democratic nominee also was expected to announce plans to expand the Drug Enforcement Administration, if elected.

Republican vice presidential candidate Dan Quayle planned to address a business group in Kansas City, Kan., before traveling on to Nebraska and Iowa. Democratic counterpart Lloyd Bentsen was seeking votes in three Southern cities - Memphis, Tenn.; Greenville, N.C.; and Palm Beach, Fla.