In Florida's perpetually unpredictable politics, a couple of consistent rules of thumb have held true about gubernatorial primaries.

You can count on Republicans to nominate the most credibly conservative candidate and Democrats to nominate the establishment favorite, usually a cautious centrist. The trend has held through throughout modern history. Yes, Tom Gallagher ran far to the right of Charlie Crist in 2006, but I said credibly conservative and nobody bought Gallagher's sincerity on that front.

The latest polls indicate there is a good chance those truisms will hold true again this year.

Public polls released last week by Mason-Dixon and Florida Atlantic University showed former U.S. Rep. Gwen Graham of Tallahassee, the daughter of former Sen. Bob Graham, leading the other four major candidates by 9 percentage points (Mason-Dixon) or 4 points (FAU). On the Republican side those polls showed U.S. Rep. Ron DeSantis leading Agriculture Commissioner Adam Putnam by 9 percentage points and 12 percentage points.

Both those races have big chunks of the electorate undecided, so nobody has the nomination locked down. The five-candidate Democratic primary is especially unpredictable, as it could take a mere 25 percent of the vote to win.

We're also living in a climate where Donald Trump won the presidency and Bernie Sanders gave Hillary Clinton a serious challenge. Conventional political wisdom doesn't count for much any more.

This year's Democratic primary is unlike any other in modern history. It features more serious contenders than Florida Democrats have seen in decades, and the party establishment is not nearly as united behind Graham as it was behind, say, Bill McBride in 2002, Alex Sink in 2010, or Crist in 2014.

What's more, the most liberal wing of the party appeared more fired up than ever before and, in Andrew Gillum and Chris King, have stronger candidates running to the left of the field than anyone since Janet Reno in 2002.

King, a Winter Park investor, preaches the gospel of big, bold ideas, such as free community college and trade schools and sweeping reforms to Florida's criminal justice system.

"Over the last 20 years, we haven't given (voters) anything to be excited about," he said. "As Democrats, we've gotten real good at losing. We've lost 21 of 25 statewide elections since 2000. The last time we won this race, I was a freshman in high school."

Gillum, easily the most charismatic in the field, offers a similar message and says the Democratic base also can get more energized to have a candidate that looks like a big chunk of the Democratic electorate. He is African-American.

"People do want to see themselves reflected. They'll never believe that Gwen Graham, Philip Levine, Chris King or Jeff Greene will be a better representative of their interests than I will be," he said.