Clinton's aides initially signaled she would virtually concede Wisconsin, and the former first lady spent less time in the state than Obama.
Even so, she ran a television ad that accused her rival of ducking a debate in the state and added that she had the only health care plan that covers all Americans and the only economic plan to stop home foreclosures. "Maybe he'd prefer to give speeches than have to answer questions" the commercial said.
Obama countered with an ad of his own, saying his health care plan would cover more people.
In San Antonio on Tuesday, Obama said her idea to freeze the monthly rate on adjustable rate mortgages for at least five years would raise rates on new mortgages. "Even more families could face foreclosure," he said. "That's why one economic analyst called her plan disastrous."
The campaign grew increasingly testy over the weekend, when Clinton's aides accused Obama of plagiarism for delivering a speech that included words that had first been uttered by Deval Patrick, the Massachusetts governor and a friend of Obama.
"I really don't think this is too big of a deal," Obama said, eager to lay the issue to rest quickly. He said Clinton had used his slogans, too.
Even before the votes were tallied in one state, the campaigners were looking ahead.