But she added, "We're not taking a single vote for granted," and Clinton will be campaigning all over the state on Obama's behalf.
Obama's running mate, Vice President Joe Biden, visited Cleveland on Sunday. He told a crowd at a high school that Romney and his running mate, Paul Ryan, are "running away from what they've stood for the last decade faster than you can imagine."
"But like a little kid, they can't run away from their shadow until the sun goes down," Biden said. "It's going down Tuesday."
Ryan started his day with a brief appearance at Lambeau Field, where he tailgated with fellow Green Bay Packers fans ahead of the team's 31-17 win over the Arizona Cardinals. He left before kickoff for Mansfield, Ohio, where he focused on shuttered auto plants and defense cuts in a state where Romney's opposition to the 2008 federal auto bailout of the U.S. auto industry has hurt the GOP. Mansfield was home to plant that made body parts for General Motors before the company's restructuring, when it was shut down.
"It's not going the right way in some places in America, and you know what it doesn't have to be like this. We don't have to settle for this," Ryan said. "This may be the best that President Obama can do, but it is not the best that America can do."
The polling numbers are slightly different in the battlegrounds, where Obama holds a small edge in more states than Romney. But most of those leads are well within the polls' sampling errors.
Obama ends his blitz Monday with three rallies with rocker Bruce Springsteen in Madison, Wisconsin; Columbus, Ohio, where he'll be joined by rapper Jay-Z; and Des Moines, Iowa. First lady Michelle Obama will introduce the president to a crowd in Iowa, where Obama's 2008 Democratic campaign took off with a surprise win in the caucuses there. The couple then will head to Chicago, where they'll spend Election Day.
Romney's other stops include Sanford, Florida; Lynchburg and Fairfax, Virginia; Columbus, Ohio; and a finish in Manchester, New Hampshire, before making the short trip to Boston, where he'll spend Election Day.