John F. Kerry promoted his economic message in this strapped battleground state for the second day in a row, blasting the Bush administration on job losses and the news that Medicare premiums for doctor visits will go up 17 percent next year.

"Let me ask you something: Who are they going to send the bill to?" the Democratic challenger asked a rally of 12,000 on Saturday. "Are they going to send the bill to Halliburton? Are they going to send the bill to Ken Lay at Enron? You bet they're not. They're going to send the bill to our senior citizens. They're going to send the bill to all of you."

Kerry spoke to a receptive, largely labor audience as he accused the administration of abandoning seniors and keeping drug costs high to pander to drug companies. He promised to provide a plan that would lower premiums, allow seniors to import cheaper drugs from Canada and allow Medicare to buy drugs in bulk to keep costs down.

The increase in premiums is the largest in four decades and will go into effect next year. Steve Schmidt, a spokesman for the Bush-Cheney campaign, shot back that Kerry has a record of "blocking . . . medical liability reform," which keeps health care costs high.

Seeking maximum advantage from the Medicare news, the Kerry campaign will launch an ad about Medicare that shows Bush at the Republican National Convention on Thursday night, saying seniors will be getting "immediate help," juxtaposed with the next day's announcement of the premium increase.

Kerry and running mate John Edwards and their wives are spending the weekend covering the Midwest battleground of Ohio, Pennsylvania, Wisconsin, Iowa and Michigan.

In Wisconsin, Edwards traveled the rural roads hosting a rally on a family-run dairy farm in Newport Township and a second late-afternoon gathering in Waukesha. At a farm owned by Don and Anita Nelson, about 300 people, some sitting on bales of hay, applauded and cheered as Edwards mentioned the Medicare premiums. "We have the largest increase in Medicare history . . . it is on this president's watch," he said. "People can't just keep paying this."

At the rally in Waukesha, Edwards was introduced by a nervous Tom Beug, a Republican businessman who fumbled his lines and was subjected to boos, until he explained to the crowd of about 600 that he was supporting Kerry. "I'm here to tell you: George Bush has been a real disappointment to me," Beug said.

Pushing their economic message represents a new strategy in the campaign to focus on domestic issues and demonstrate that Bush is disingenuous and has broken promises made in 2000. "You can't believe one thing they say, because they are the biggest say-one-thing-do-another administration in the history of the country," Kerry said.

In addition to a couple of large partisan rallies Saturday, Kerry did his best to appeal to swing voters. In the middle of his remarks here and apropos of nothing, he mentioned that he is a hunter and owns a gun. A couple of hours later, he went skeet shooting with former senator John Glenn. Kerry made four of 10 shots.

Kerry led a bus caravan for two days through Ohio, a state that has lost 230,000 jobs in the past four years. As of July, the unemployment rate in Akron was 7.3 percent. No Republican has ever won the presidency without winning Ohio; Bush won in 2000, but recent polls show the race competitive here.

Kerry tempered his attacks on Bush, sticking to policy. But those who introduced him made pointed statements about Kerry's and Bush's military service, suggesting that with polls showing Bush up in the polls, the campaign may be concerned that attacks on Kerry's service record resonate.

"In the past four years, George Bush has served the American worker in the same way he served the Texas National Guard. He was absent without leave," said John Wagner, executive secretary of the local AFL-CIO.

"We proposed an agenda for America, and they proposed a slander campaign against the decorated veteran," said Rep. Timothy J. Ryan (D-Ohio), who called it "disgusting" to divide the nation's veterans. Akron's mayor, Donald L. Plusquellic, weighed in, saying, "John Kerry was in Vietnam, and George Bush was not. . . . George Bush was hiding in the woods in Alabama."

Kerry also raised his military record, asking those in the audience to assure their friends he could lead in a time of war. "Republicans are trying to scare America. All they wanted to talk about is the war on terror," he said. "Let me tell you something. . . . I defended my country as young man and will defend it as president. . . . I know how to fight a war on terror, and one that is smarter and more reflective that this president is doing."

Edwards, who on Friday launched a bus tour of Wisconsin, has stopped his caravan a few times between campaign events to greet small knots of supporters along the highway. Saturday he pulled off the road to chat briefly with a small crowd in Briggsville. As he criticized Bush's stewardship of the economy and the Iraq war, Rick Bernbrode, 57, stood silently on the sidelines holding a sign asking Edwards to "please advise Mr. Kerry to apologize to all Vietnam veterans for his lies."

Bernbrode said he served in the Vietnam War in 1967 and 1968 and spent three months in a hospital after being wounded in action. "I earned my Purple Heart," he said.

Still, Bernbrode did not seem excited about Bush, although he said he will probably vote for him. "They're all probably crooks, so I just vote for who I think is the lesser of two evils."

Kerry and campaign officials dismissed some post-convention polls that show Bush with an 11-point lead. "They're going to get a bounce out of the convention, but we'll be back," Kerry told his fellow skeet shooters in Edinburgh, Ohio. He dismissed a suggestion that one of the clay pigeons should be painted with an image of Sen. Zell Miller (D-Ga.).

Williams is traveling with Edwards.