If you needed any proof that Republicans are worried about a looming runoff, look no further than Sunday’s gubernatorial debate.

That’s when Gov. Nathan Deal, instead of lobbing a softball at his Libertarian rival, unloaded a double-barreled attack questioning his support for a Medicaid expansion and criticizing the millions of dollars in federal grants his technology firms accepted.

Georgia Democrats and Republicans are warily eyeing the third-party candidates in the two races atop the ballot, mindful that voters could be headed to two more grueling contests if no candidate tops 50 percent on Nov. 4. They are worried for very different reasons.