MIAMI - If Donald Trump wins Marco Rubio's home state and John Kasich's home state on Tuesday, he'll take a massive leap towards securing the Republican nomination and likely end both of their campaigns.

You wouldn't know it from watching Thursday night's debate, however, where the field seemed content to go gentle into that good night. The debate featured polite disagreements but few outright attacks and a number of substantive exchanges over issues like trade and foreign policy.