"This is not the time to invite new deficits and high interest rates that could stifle both our growth and our hopes," Mr. Gore said in Washington, taking swipes at the "other side."
In Green Bay, Wis., Mr. Bush charged that a Gore administration would revive the era of "big government."
"My opponent seemed interested in reinventing government. Now he seems interested only in expanding it," the Republican presidential nominee told supporters at a container factory.
"I see our record surplus as an opportunity to save Social Security, pay down debt, provide families with tax relief, improve public education and extend our prosperity," Mr. Bush said, trying to draw distinctions with his Democratic rival.
"He sees it as the foundation for permanent expansion of government, and his plan to spend it all would threaten our current prosperity."
Each candidate touted his economic platform â€“ and trashed his opponent's â€“ as the two continued to set the stage for Tuesday's debate in Boston, the first of three next month.
Both men, running neck and neck in the public opinion polls, shifted off their messages from the start of the week â€“ Medicare for Mr. Gore and education for Mr. Bush.
On Friday, each plans to discuss energy and environmental policy, then hunker down over the weekend for some serious debate preparation. Mr. Gore will work in Sarasota, Fla., Mr. Bush back home in Texas.
Speaking first on Thursday at the Brookings Institution in Washington, Mr. Gore sought to cast the election as a series of tough choices.
"Prosperity itself will be on the ballot," he said, pledging to make the "right choices," no matter how unpopular, to ensure a resilient national economy.
Mr. Gore said he would be a president who takes "responsibility for our economy," not one who tries to "take liberties with it." And in a swipe at "the other side," he railed against Mr. Bush's call for $1.3 trillion in across-the-board tax cuts over the next 10 years.
It "mostly helps the very wealthy at the expense of middle-class families and could wreck our good economy in the process," Mr. Gore said.
His program for $500 billion in targeted tax cuts was better, he said, because it would make the "right investments in education, health care, a clean environment and a secure retirement," while also bolstering the national defense, balancing the budget and paying off the national debt.
"These are tough choices, but they're the right choices," Mr. Gore said. "Within eight years, government spending would be the smallest share of national income that it's been in 50 years."
It all boils down to a "single, fundamental question," he said. "Will we use our prosperity and our record surpluses to prepare for the future?"
Under his fiscal plan, Mr. Gore would devote the largest share of the projected budget surplus to pay off the federal debt by 2012. But Mr. Bush calls the surplus "the people's money," some of which should be returned to them.
"A surplus, after all, means a surplus of tax collection," Mr. Bush said Thursday. "It means Americans have been overcharged. And they should see some of that money back again."
Mr. Bush, who allowed several weeks ago that he had not done a good job of selling his tax-cut plan, has been explaining it in more detail this week.
He has proposed using half the projected $4.6 trillion budget surplus over the next 10 years to shore up Social Security and another quarter of the surplus to finance other top priorities, including education, the military and a new prescription drug benefit for the elderly.
The rest could be used for tax relief, Mr. Bush said.
Saying that Mr. Gore's proposed spending for health care, education and the environment could "amount to over $2 trillion in bigger government over 10 years," Mr. Bush invoked the name of a previous president from Texas â€“ though not his father.
"He's proposing the largest increase in federal spending in 35 years, since the presidency of Lyndon Baines Johnson," Mr. Bush said.
In discussing Mr. Gore's proposals, the governor tripped over a number, saying the vice president was calling for "over 200,000 new or expanded federal programs," instead of the 200 cited on his prepared text.
During his 1996 State of the Union address, President Clinton declared the "era of big government is over," but "apparently the message never took" with his vice president, Mr. Bush said.
"For him, big government has never really been dead. It's simply been biding its time, waiting for its next chance," he said. "The vice president would like that chance to come next January."
Mr. Bush said his experience as a governor would also make him a better steward of the nation's prosperity.
"I'm running against a man who's never really run anything," Mr. Bush said. "He's been a legislator; he's been a Number 2 man in an administration. But governors, like CEOs, are on the front line. We make decisions."