HOUSTON -- Voters in the country's fourth-largest city must now decide whether an openly gay woman should lead Houston for the first time or if a former city lawyer will become the city's second black mayor.

City controller Annise Parker topped a field of four major candidates running for mayor on Tuesday, and former city attorney Gene Locke edged a big-spending city council member to earn the second spot in a runoff next month.

A victory by Parker, 52, whose sexual orientation never was an issue in six years on City Council and six years as city controller, would make Houston the nation's largest city to be led by an openly gay person.

“I absolutely believe in my core I'm the best qualified candidate,” she said after voting results came in Tuesday night.