MIAMI — Convinced that his surprising victory in Michigan represented a turning point, Senator Bernie Sanders and his advisers are maneuvering and spending aggressively to pull off a huge upset on Tuesday — a victory in the Ohio primary — by focusing on Hillary Clinton’s past support for trade deals that are deeply unpopular in the Midwest and other key states in his updated battle plans.

Mr. Sanders seemed newly energized and tactical as he sat by a pool at his Miami hotel and predicted that Tuesday’s win was just the beginning of a phase of the campaign that he would dominate. Saying that coming primaries and caucuses looked unusually promising for him, he described plans to crisscross the country arguing that Mrs. Clinton championed policies that wrecked lives. He also said he would tell voters that he was the strongest candidate to put up against Donald J. Trump, the Republican front-runner.

“We are heading to the Midwest. We are going to Ohio. We are going to Illinois, going to Missouri, drop into North Carolina,” Mr. Sanders said. “These states in the Midwest are going to respond to us and our message in the same way Michigan workers did, and that is, ‘We need an economy that works for all of us and not just the 1 percent. We need a trade policy that creates jobs in America, not in China or in Mexico.’ ”

“I think the future now bodes well for us because we are moving out of the Deep South, where we have not done well,” he continued.