BOCA RATON, Fla. — Republican presidential primaries have for decades been orderly affairs, with any momentary drama mitigated by the expectation that the party would inevitably nominate its tested, often graying front-runner.

But as the 2016 White House campaign effectively began in the last week, it became apparent that this race might be different: a fluid contest, verging on chaotic, that will showcase the party’s deep bench of talent but also highlight its ideological and generational divisions.

As Democrats signal that they are ready to rally behind Hillary Rodham Clinton before their primary season even begins, allowing them to focus their fund-raising and firepower mostly on the general election, the Republicans appear destined for a free-for-all.

“I can think of about 16 potential candidates,” said Haley Barbour, the former governor of Mississippi and a veteran of Republican presidential politics dating to 1968. “Almost every one of them have a starting point. But there is no true front-runner.”