COLUMBUS, Ohio (AP) - His nomination assured, John McCain got an early jump on the general election this week with a swing through Midwestern states likely to be pivotal in the fall and a fresh line of criticism against Barack Obama.

"I will compete very strongly here in the heartland of America," the Republican nominee-in-waiting said in Ohio, underscoring the importance of the state and the region as he embarks on an eight-month effort to cobble together the 270 electoral votes needed to win the White House.

It was fitting, then, that McCain chose this setting - a state that gave President Bush the 2004 election in a swing-voting region - to step up his rhetoric against the man he considers his most likely opponent this fall.

"I will fight every moment of every day in this campaign to make sure Americans are not deceived by an eloquent but empty call for change," McCain said after winning the Wisconsin primary. It was a thinly veiled suggestion that the Illinois Democrat, who has now won 11 straight primary and caucus contests over Hillary Rodham Clinton, lacks the experience, judgment and character a president needs.

Well into the week, however, a character controversy of his own overshadowed McCain's message.

At a news conference in Toledo on Thursday, McCain was forced to respond to published reports that alleged he showed favoritism to clients of a female telecommunications lobbyist. A New York Times report said top McCain aides became "convinced the relationship had become romantic."

With his wife, Cindy, beside him, he denied any romance or impropriety.

"It's not true," McCain said. "At no time have I ever done anything that would betray the public trust."

"We will move forward," he declared and continued his Midwest trek.

With Obama and Clinton still fighting for the Democratic nomination, the GOP's likely standard-bearer is laying groundwork now for the fall by visiting key states and trying to define his opponents, particularly Obama.

Thus, McCain took his sharper criticism of Obama to five middle America states this week.

He began in Wisconsin, at a county GOP dinner and a get-out-the-vote rally. By Tuesday, he was in Ohio celebrating a Wisconsin victory that inched him closer to the 1,191 convention delegates he needs to clinch the nomination.

McCain also stopped in Illinois on Wednesday and toured a Ford Motor Co. assembly plant in Michigan on Thursday. He rounds out the week Friday in Indiana with a town-hall style meeting.

The Arizona senator was also raising cash in each state. He kept a busy fundraising schedule for someone who doesn't like the chore. "We've got a lot of work to do," McCain acknowledged.

His attention to this region is no surprise.

The Midwest has been hotly contested in recent presidential elections. Both Republicans and Democrats plan to focus on it again this fall.

Some states here have a long history of solidly backing one party or the other. Indiana, for one, is a strong Republican state, where George W. Bush won big in both campaigns. Illinois, conversely, has been a predominantly Democratic state, won comfortably by John Kerry in 2004 and Al Gore in 2000.

But most others are considered swing states.

No Republican has ever won the presidency without winning Ohio. Bush saw very narrow victories here twice.

Wisconsin, Minnesota and Michigan all sided with Kerry and Gore - but by margins of less than 5 percentage points.

One Midwestern state, Iowa, split in the last two elections. In 2004, Bush won by 1 percentage point four years after losing to Gore by the same margin.

Since 1900, Missouri has backed every presidential winner but one - it went with Adlai Stevenson from neighboring Illinois in 1956. Bush had one narrow and one comfortable win there.

Economic issues dominate campaigns here. Once laden with industry and rich with agriculture, the region is struggling; job losses and recession fears weigh heavily on voters' minds.

McCain focused on that this week.

"We're in an information technology revolution, and it has changed the world. It has changed America. But we can't leave people behind," he said in Columbus. "We have to help them through this transition."

Earlier, in Brookfield, Wis., McCain explained how he might win in Wisconsin and other Midwestern states. "I can appeal not only to our Republican base but to independent voters," he said.

For all the general election maneuvering, McCain remains mindful that Mike Huckabee is still technically competing for the GOP nomination.

So McCain continues to campaign in states with upcoming primaries even as he looks ahead.

In Yellow Springs, Ohio, on Wednesday, he declared, "I intend to win the state of Ohio, both a week from Tuesday and in the general election in November!"