2018 was supposed to be Adam Putnam’s year. But tweets from President Donald Trump and one of his own — doomed his campaign, Scott Maxwell writes.

Adam Putnam worked all his life to be governor.

And he was good at it — the consummate Southern politician with a broad, toothy smile, always-pressed shirts and a southern drawl that would impress Foghorn Leghorn.

He remembered names, backslapped with the best of ’em, won a legislative seat at age 22 — and then spent the next 22 years campaigning for Congress, agriculture commissioner and finally governor along the back roads of Florida where he spoke at local Lincoln Day dinners and posed for pictures at the annual Possum Festival.

For Putnam, 2018 was supposed to be more of a coronation than a campaign.

It was all derailed by a single tweet.

President Donald Trump formally endorsed Ron DeSantis on June 22, saying: “He will be a Great Governor & has my full Endorsement!”

Before then, many Floridians didn’t even know what a DeSantis was.

Maybe a perfume fragrance. Or a car model that stopped production in the ’50s.

As it turns out, DeSantis was the name of a not-so-well-known congressman from North Florida who really, really liked Trump … which made Trump really, really like DeSantis.

So Trump endorsed him — and DeSantis’ numbers skyrocketed. He went from polling at around 17 percent the week before Trump’s tweet to 43 percent three weeks later.

Putnam went from a 2-to-1 favorite to a political punching bag.

By the end of the campaign, some Republicans suggested Putnam’s best hope was to lose with dignity.

His loss Tuesday — getting destroyed by DeSantis — marked a stunning fall for a guy once viewed as the party’s brightest rising star.

Putnam, after all, had followed all of the rules … except the Republican Party’s rules aren’t what they used to be.

Paying your dues doesn’t matter as much as raging against the swamp. And Putnam couldn’t rail about the swamp … because he was up to his eyeballs in it.

Virtually every deep-pocketed interest had its hooks in Putnam. Sugar, lawyers, insurance, Realtors, developers, grocers, theme parks. If there was an industry with an army of lobbyists, that army was rallying behind Adam Putnam.

And Putnam reveled in the money and special-interest adulation … until he choked on it.

Which brings us to the second tweet that doomed Putnam — the one last year when he declared himself a “proud NRA sellout.”

Putnam viewed the tweet as little more than a tongue-incheek way to troll liberals and rile up his base. But it backfired. Big time.

This would end up being the election cycle in which Florida voters would mourn the slaughter of 17 students and teachers in Parkland. Suddenly, sycophantic gun jokes didn’t seem so cute.

Millennials, sick of seeing older generations offer only thoughts, prayers and shrugs in response to mass shootings, took to the streets — and to the grocery aisles of Publix where they told Florida corporations they were tired of seeing the businesses they patronize prop up the gun lobby’s political tools.

But the one word that really doomed Putnam was “sellout.” See, people can respect an ardent defender of the Second Amendment. Nobody respects a sellout.

And Putnam ended up wearing

the “sellout” label he gave himself like an anvil — because there were so many instances of him doing the bidding of his financiers.

When Publix got failing grades from the state’s health inspections, Putnam’s agriculture department changed the entire grading system, so no one could “fail.” When polluters complained that cleanwater standards were too tough, Putnam responded: “We don’t need the EPA.” That message doesn’t float in a state now coated with algae.

DeSantis may not have had much of a track record. But if he had a single example of standing up to vested interests — such as when DeSantis voted against agriculture subsidies — it was one more example than many people could recall with Putnam.

Plus, DeSantis had some impressive credentials: former Navy JAG officer, Bronze Star recipient and graduate of Yale University and Harvard law.

Package all that with a Trump tweet, and DeSantis had a campaign that was tough to stop.

Putnam was reduced to running ads that featured him awkwardly baling hay to try to connect with the working man and trying to tell primary voters that, while he too liked Trump, he hoped his fellow Republicans would ignore the president and his tweets … just this once. It didn’t work. Heading into November, DeSantis will have the challenge of convincing independent voters that he offers something more than just a bromance with Trump. But in an August primary, the Trump seal of approval, coupled with Putnam’s personification of the status quo, was enough.