TOLEDO, Ohio — The ad from Mitt Romney showed up on televisions here early Saturday morning without the usual public announcement that both campaigns typically use to herald their latest commercials: Chrysler, a bailout recipient, is going to begin producing Jeeps in China, an announcer says, leaving the misleading impression that the move would come at the expense of jobs here.

And so began the latest, and perhaps most important, attempt by Mitt Romney to wrest Ohio into his column. His effort to do so is now intently focused, at times including statements that stretch or ignore the facts, on knocking down what is perhaps the most important component of President Obama’s appeal to blue-collar voters in Ohio and across the industrial Midwest: the success of the president’s 2009 auto bailout.

Mr. Obama’s relatively strong standing in most polls in Ohio so far has been attributed by members of both parties to the recovery of the auto industry, which has helped the economy here outperform the national economy. At the same time, the industry’s performance and the president’s claim to credit for it appear to have helped Mr. Obama among the white working-class voters Mr. Romney needs.

With the race under most expected circumstances coming down to Ohio, and Ohio potentially coming down to perceptions of how the candidates view the auto industry, Mr. Romney has spent the last few days aggressively trying to undercut Mr. Obama’s auto bailout narrative.