• by Philip Rosenstein , Staff Writer, March 15, 2016

Today could turn out to be a primary watershed before the conventions in July. Republicans and Democrats vote in five states: Florida, Ohio, Illinois, Missouri and North Carolina.

The most pivotal contests on the GOP side are Ohio and Florida.

Ohio Gov. John Kasich has been polling ahead of Donald Trump, with a 3.7 point average lead according to RealClearPolitics. He could secure a win in his home state, where he boasts a strong approval rating as governor.

For Sen. Rubio, the prospects in his home state look much more bleak. Rubio is trailing far behind Donald Trump, with more than an 18-point deficit in RCP’s polling average.

Mitt Romney has been campaigning with Gov. Kasich in Ohio, though has held off on a true endorsement. His decision to tag along in Ohio instead of Florida may suggest the GOP establishment is coming to terms with the futility of Rubio’s campaign.

While Rubio aides and supporters may argue that the polls are misrepresenting actual support for him, it sounds like wishful thinking. Anti-Trump groups have bombarded Florida with ads attacking the front-runner, with little to no results. Didn’t Jeb Bush try that already?

Our Principles PAC, whose founder Katie Packer was Mitt Romney’s deputy campaign manager in 2012, has spent over $5.5 million on-air so far attacking Trump, with $2.2 million of that spent in Florida. They’ve also pulled out all the stops with a semi-explicit ad highlighting Trump’s misogyny.

If Trump can win in Florida and Ohio, which are both winner-take-all states as far as delegates go, he will be well on his way to the nomination. If he wins one of those states, he’ll still be far ahead, considering Sen. Ted Cruz is not really competing for wins in either Florida or Ohio.

If he loses both, the conversation will shift and the chance of a brokered convention in July becomes more likely.

On the Democratic side, Hillary Clinton is polling ahead of Sen. Bernie Sanders in all states, but Missouri, where polling has been particularly scant. After last week’s Michigan surprise, Sanders supporters will be fighting for another upset.

If Sanders can pull off a key win or two, a whole other conversation will begin within Democratic ranks. If not, Hillary Clinton can virtually seal the deal with a convincing sweep tonight.