LARGO, Fla. -- For the first half of their second debate, four contenders for Florida's Democratic gubernatorial nomination were about as civil as can be and hardly differed on issues of gun control and opposition to for-profit schools.

But mentions of Syrian refugees and a campaign contribution to U.S. Sen. Marco Rubio heated up the debate inside a Largo, Florida, high school Saturday night.

Businessman Chris King chastised former U.S. Rep. Gwen Graham for supporting failed legislation that would have added a layer in the processing of Syrian refugees.

Meanwhile, Tallahassee Mayor Andrew Gillum criticized former Miami Beach Mayor Philip Levine for making a donation to Rubio, a Republican.

Saturday night's live-televised debate is one of a series of forums scheduled before the August primary.