President Bush and John F. Kerry dueled over the economy as they campaigned Saturday in two of the nation's most jobs-sensitive states, intensifying their fight for control over a dozen-and-a-half battlegrounds likely to decide the election.

In Ohio, which has lost tens of thousands of manufacturing jobs, Bush defended his record and said with another four years, he would make the economy stronger. Acknowledging that workers in Ohio remain nervous about jobs going overseas, he said, "We must have a president who understands that in order to keep jobs at home." At a stop here southeast of Pittsburgh, Kerry questioned Bush's record and commitment, scoffing at his contention that the economy had turned a corner. "The last time we had a president who talked about turning the corner . . . was Herbert Hoover," he said.

Bush advisers see August as a critical period in the presidential race and have adopted a strategy designed to suppress Kerry's post-convention bounce, shore up Bush's standing in the battlegrounds and come out of their convention at the beginning of September with the race even. They worry that if Kerry begins the final two months of the campaign with a clear lead, the president's prospects for winning a second term will be in danger.

Bush and Kerry nearly crossed paths Saturday, as their multi-vehicle caravans rolled through western Pennsylvania. That will happen again Wednesday when the two candidates campaign around Davenport, Iowa. Their movements underscored the targeted geographic battle underway. Bush and Kerry are engaged in trench warfare in local media markets throughout the battleground states, with travel and messages dictated accordingly.

At this point, Kerry and Bush advisers agree that neither candidate has gained a clear advantage in the battleground states, which stretch from one coast to another and include targets in every region.

A mid-campaign look at those states, based on interviews with Kerry staffers and officials of independent groups supporting his candidacy, state delegation leaders at the Democratic National Convention, Bush campaign aides and GOP officials who set up a counter-headquarters in Boston, as well as state polls, suggests that Campaign 2004 remains extraordinarily competitive with 93 days left to the Nov. 2 election.

Kerry's convention energized the Democrats, and his campaign hopes to seize control of the race with its cross-country trip over the next two weeks. But the first national poll released since Kerry's Thursday night acceptance speech showed little gain for the Democrats.

The Newsweek poll showed Kerry and running mate John Edwards leading Bush and Vice President Cheney by 52 to 44 percent, a net gain of 2 percentage points from the magazine's poll in early July.

When independent Ralph Nader was included, Kerry led Bush by 49 to 42 percent, with Nader at 3 percent, a 4-point gain since early July. Smaller and therefore less reliable nightly samples suggested that Kerry had picked up more support after his acceptance speech. Later polls may show a clearer pattern.

The close race has heightened the intensity of campaigning for the crucial battlegrounds. Here is a region-by-region look at the race:

In the South, Florida remains the main battlefield, with Democrats arguing that several political developments have improved the ticket's chances in the state where Al Gore came achingly close to winning last time. An apparent split in the Miami Cuban community over new Bush-ordered restrictions on travel and remittances to Fidel Castro's country and the growth of non-Cuban Hispanic population in the Orlando area can help Kerry. But Republicans say the continued influx of tax-averse retirees from colder climates will offset any Democratic gains, and they believe Gov. Jeb Bush (R) will once again find the votes to help his brother.

The addition of Edwards to the ticket has put his home state of North Carolina into play, and Republicans agree that they cannot assume the state, which has gone for the GOP nominee six times in a row, is safely Bush's. Several of the state's major industries -- notably textiles and furniture -- have been hurt by imports, but it remains an uphill fight for the Democrats.

Democrats also have talked from time to time about -- and committed some TV dollars to -- Louisiana, Virginia, Arkansas and Tennessee. Republicans dismiss claims they are battlegrounds and some Democrats not working for Kerry agree.

In the Northeast, the big prize is Pennsylvania, which Vice President Gore carried by 4 percentage points. In 2000, Bush fell well short of the margin he needed out of the Philadelphia suburbs. Republicans claim that Bush's 31 visits to the state, plus his initiatives on education and prescription drugs, have boosted his stock.

But Gov. Edward G. Rendell (D) said that Kerry will win because Bush's stands on social issues hurt him in the Philadelphia suburbs and the economy is weak in the western parts of the state where Bush's conservative social issue stands are popular. Campaigning with Kerry this weekend, Rendell exhorted Democrats in central and western Pennsylvania to shave Bush's 2000 margins to assure a big Kerry victory.

Another battleground is New Hampshire, which Bush narrowly carried. The economy has improved in the last two years, but Democrats say many who had high-wage jobs in the high-tech sector have been forced into low-wage service jobs. Kerry is a neighbor and unlikely to ignore the state, as Gore did. Republicans say they can label him just "a typical Massachusetts liberal," and defeat him, as they did Michael S. Dukakis in 1988.

West Virginia was one of the surprises in 2000. The traditional Democratic bastion went to Bush after he made a late visit with Charlton Heston, then president of the National Rifle Association. Democrats say they will not be caught sleeping again. Kerry already has campaigned extensively in the state, emphasizing his credentials as a hunter and showing off his support among its many veterans. Democrats say their candidate for governor, Secretary of State Joe Manchin III, will help the whole ticket. But Republicans do not buy the idea of reverse coattails and say that Kerry is not trusted in coal country because of his strong environmental views.

In the Midwest, more states -- and far more electoral votes -- are up for grabs than anywhere else.

No Republican has ever won the White House without Ohio, and Kerry has made it a principal target. No state has lost more industrial jobs in the past three years, and signs of recovery have been slow to appear, as Bush acknowledged Saturday.

Republicans have control of every statewide office, and the Democratic Party may be the weakest in any major state. But independent liberal groups have sent in hundreds of people to begin signing up new voters in hard-hit areas, and it appears questionable that the GOP can overcome the economic drag. Bush cannot afford to lose Ohio and will be there regularly.

Democrats are less hopeful about converting Missouri to the Kerry column. Bush has strength in the suburbs and in the rural areas, where he pounded home a conservative, value-laden message Friday. Democrats have suffered from a divisive gubernatorial primary.

Three states on the Upper Mississippi River -- all closely won by Gore -- look inviting to the Bush campaign. Minnesota, once a liberal bastion, has been trending Republican, with the GOP winning the governorship and an open Senate seat in 2002. Suburban growth around the Twin Cities was the key to those wins, and Kerry must find a way to reach some of those tax-conscious voters to keep the state.

Wisconsin was the site of a major battle in 2000 and will be again. Kerry has led narrowly, but Gov. Jim Doyle (D) says it would be a mistake for the campaign to count it securely in his corner.

Iowa, where Kerry and Edwards finished one-two in the January caucuses, is perhaps the least likely of the three to switch to the GOP. Democrats have launched a massive absentee vote program, and the state party is one of the most effective in the country. But farm prices are uniformly high and the economy is brighter than in many other midwestern states.

Michigan, which also went for Gore, is the opposite economically, continuing to suffer job losses. Republicans have slipped badly in the past few elections, losing a Senate seat and the governorship. Kerry has been viewed with skepticism by the auto industry, the state's main employer, for his environmental positions and Democrats say he has work to do to nail down his lead. But it would be remarkable for Bush to stage a comeback in a state with 6.5 percent unemployment.

In the West, Arizona, New Mexico, Nevada and Oregon appear to be the most closely contested states. Arizona Gov. Janet Napolitano (D) says her polling shows Kerry behind, "but not by a lot," and says the changing demographics of the state -- with Hispanics and young families moving in to fill an expanding workforce -- will make the state competitive. The prescription drug benefit has not proved popular among seniors so far, but the conservative base in Arizona remains sizable and Sen. John McCain (R), the state's most popular public figure, is heading the Bush campaign.

Oregon is one of the Gore states where Republicans see an opportunity. It has had a continuing tax revolt, with successful initiatives to limit or roll back taxes, and Gov. Ted Kulongoski (D) said the tax issue could be Bush's best and Kerry's toughest. Conservative organizations have qualified an initiative to ban gay marriage. But the state has high unemployment and Bush's environmental policies remain controversial.

New Mexico, which Gore carried by 366 votes, is also a major target for Bush. His resource and public lands policy is popular with business, but -- as in Arizona -- polls show little headway for Bush in the growing Hispanic population. Both sides expect another close outcome.

The Kerry campaign has shown signs of interest in Colorado, where Democrats see a chance to pick up an open Senate seat. But Gov. Bill Owens (R) said Kerry is foolish to contest the state, and one veteran Democrat said he has told Kerry, "If you carry Colorado, you will have won by a landslide."

Broder reported from Boston.

Campaigning in the key state of Ohio, President Bush vowed to make the economy stronger if he is reelected.Next door in Pennsylvania, opponent John F. Kerry scoffed, likening Bush's record to that of President Herbert Hoover.The Democratic ticket -- John F. Kerry and John Edwards -- rallies a crowd in Pennsylvania.