COLUMBUS, Ohio — A campaign for the Democratic presidential nomination that has pivoted on race and gender could be decided here today by another divide — the state’s urban north versus the rural south, pitting Ohio’s popular governor against a cadre of big-city mayors.

While Senators Clinton and Obama have built their own campaign organizations here, they also have tried to tap into the political machines directed by successful Democratic political leaders, local analysts said.

Mrs. Clinton has the backing of freshman Governor Strickland, a former long-serving congressman from the southeastern Appalachian region. But Mr. Obama has the backing of the mayors of the state’s three largest cities: Columbus, Cleveland, and Cincinnati.

The mayors’ close ties to local political bases could be significant in a state where recent polls showed Clinton with a 6-point lead, and 1 in 10 voters were still undecided or could change their minds.

“I would rather have the mayors in the major cities (than Strickland’s backing) because that is where more of the vote will come from,” a political analyst at Ohio State University who has watched Ohio politics for more than a quarter-century, Herb Asher, said.

Ohio is a state whose political texture changes by geography and in which the social and political personality has its own Mason-Dixon line — Interstate 70, which bisects the capital city of Columbus.

The north is anchored by old industrial centers such as Cleveland, Akron, Youngstown, and, separated by farm areas along Lake Erie, Toledo. In the south, with the exception of Cincinnati, the state is rural and, to the southeast toward the West Virginia line, Appalachian coal country.