Campaigning again after sidelining himself during the Democratic National Convention, where Kerry accepted his party's nomination to run against Bush in the Nov. 2 election, the president charged that his rival lacked any "signature achievements" in his nearly 20-year Senate career.
"My opponent has good intentions, but intentions do not always translate to results," Bush told a cheering crowd that packed a baseball stadium still soggy from an earlier rain in Springfield, Missouri.
When choosing a president, "results matter," Bush said.
Bush on Friday undertook a bus and plane trip through Missouri, Michigan, Ohio and Pennsylvania, four of the most contested states, while Kerry and Sen. John Edwards, his running mate, began a two-week cross-country trip by bus, train and boat and plane.
Bush will wrap up two days of campaigning with a rally Saturday afternoon in Pittsburgh, just hours after Kerry speaks in a nearby suburb.
Kerry started the day Friday with an early morning rally along Boston Harbor.
"Americans are playing by the rules while a whole group of people are writing the rules for themselves and leaving the rest of America out," Kerry said. "We're going to change that around. Help is on the way for the average person in this country."
The end of the convention marked the beginning of the publicly funded part of the campaign, reports CBS News Correspondent Jim Axelrod. Both sides have $75 million to spend, but Kerry and Edwards have to stretch it out over a month longer.
In an afternoon rally in Scranton, several thousand cheering supporters filled at least three city blocks, hanging out of office buildings and garages to see Kerry.
"These are dangerous times today," Kerry said. "We're living in a world that's changed dramatically from the world of four years ago and we deserve leadership that tells the truth to the American people and helps America act like a beacon to the world."
But Bush criticized Kerry's Senate voting record on intelligence reforms.
"During eight years on the Senate intelligence committee, he voted to cut the intelligence budget, yet he had no record of reforming America's intelligence capability," said Bush, whose advisers are combing the Sept. 11 commission's recommendations to revamp the nation's intelligence-gathering ability.
"After 19 years in the United States Senate, my opponent has had thousands of votes, but very few signature achievements," Bush said in Pittsburgh.
Kerry fired back at Bush's criticism, dismissing it with a laugh as "the response to a positive campaign." He said he was behind "a long list" of legislation during his 19-year Senate career, including funding for more community police, improvements to health care and support for fisheries programs.
"They don't have a record to run on, so all they can do is attack," Kerry said.
His caravan of 10 buses and at least 11 other support vehicles rolled through Massachusetts, Connecticut, New York and Pennsylvania Friday. Kerry and Edwards brought along their wives, adult children and blockbuster actor Ben Affleck.
"Don't confuse me for being on the front bus," Affleck said after being mobbed by media outside the restaurant. He said he was riding behind Kerry's lead motorcoach in a bus.
Registered Republican Chris Smith said he became convinced Kerry would beat Bush after watching it.
"I don't like the way the present administration is handling Iraq or the National Guard," said Smith, a nuclear plant worker and Navy veteran.
During the next two weeks of campaigning, Bush will talk about helping Americans adjust to a changing economy, increasing home ownership, overhauling Social Security and letting workers opt for time off as compensation, rather than overtime pay — an issue that has riled unions, Democrats and some moderate Republicans.
Bush's remarks on the economy focused on his efforts to better educate and train tomorrow's work force. He didn't mention the White House's projecting on Friday that this year's deficit will hit a record $445 billion, further fueling a debate over the president's handling of the economy.
He sprinkled throughout his speeches another new campaign slogan: "We're turning the corner and we're not turning back."
Outside the stadium where Bush spoke, more than 100 demonstrators protested the president's 20th visit to Missouri.
Protester Steve Morrow blamed the Bush administration for the loss of his $18-an-hour job at steel plant in Kansas City, Missouri. After 31 years, he was forced to retrain for a position in heating and cooling.
"I used to make a decent living, but when my plant shut down, I had to take a job that paid only $8 an hour," Morrow said.