Ohio Gov. John Kasich, who was the last Republican standing against Donald Trump in 2016 and refused to endorse him in the general election, says in a new book that it’s time for "thinking, feeling Americans to come together in support of the Trump administration."

But Kasich — who will appear in West Palm Beach at a Forum Club of the Palm Beaches lunch on Friday to promote his book — also writes that Trump won’t get a "free pass." And in an interview with The Palm Beach Post this week, Kasich didn’t shut the door on the possibility of running for president again in 2020.

"I have no clue what I’m doing in 2020," said Kasich, who faces term limits as Ohio governor in January 2019. "I’m wondering what I’m going to be doing in the next 20 minutes. I don’t know. I really don’t. I’d like to have a voice, whether it’s through public office or whether it’s not. I think that’s going to be left to a higher power than me."

Kasich’s book is titled Two Paths: America Divided or United. He took the title from an April 2016 speech in which he described Trump’s path as one "that exploits anger, encourages resentment, turns fear into hatred and divides people. This path solves nothing, demeans our history, weakens our country and cheapens each of us. It has but one beneficiary and that is the politician who speaks of it."

Elsewhere in the book, Kasich describes the 2016 election taking place in a "post-truth environment" and amid a "spiritual disconnect."

Aside from its account of 2016, the book includes Kasich’s thoughts on leadership and "followship," his faith and his 1970 meeting, as an Ohio State University freshman, with President Richard Nixon. After sending a letter to Nixon requesting a meeting, Nixon replied and the two met in the Oval Office on Dec. 22, 1970.

"It shows that anything’s possible because I wasn’t the president of the student body…It was certainly a very fateful and important meeting in the course of my life," Kasich told The Post.

He added: "Too bad I hadn’t been there the day before — I would have met Elvis."

The famous Oval Office meeting between Nixon and Elvis Presley occurred on Dec. 21, 1970.

The race for the 2016 Republican presidential nomination initially featured 17 candidates, many of whom attacked each other. Kasich, however, tried to position himself as an above-the-fray candidate.

"I didn’t want to be the candidate who won by trading on people’s fears and sinking into the mud," Kasich writes in his new book. "Even more important, at the end of the day, I didn’t think this approach would work."

Kasich won only one primary, Ohio, but said he remains comfortable with the way he ran.

"I have not one single regret," Kasich said this week. "Not one single look-back, like ‘Why shouldn’t I have?’ or ‘Why didn’t I?’ this. Isn’t that great? I’m happy with who I am, I’m happy with my life. I’m happy with the way that people respond to me."

Kasich and Texas Sen. Ted Cruz were the final Republicans to contest Trump for the GOP nomination. At a Republican National Committee meeting in Broward County in April 2016, Cruz urged Kasich to drop out, ridiculing him as having "no path whatsoever to the nomination."

When Trump won the May 3, 2016 Indiana primary, Cruz dropped out and then-Republican National Committee Chairman Reince Priebus declared Trump the party’s presumptive nominee. Kasich, irked by Priebus’s proclamation, initially vowed to fight on but dropped out the next day.

Kasich never endorsed Trump and did not attend the Republican National Convention, even though it was held in his home state. In the November election, Kasich said he cast a write-in ballot for John McCain for president.

Kasich this week said Trump’s presidency has been a "mixed bag" so far.

He applauded Trump for "saying that Dreamers (can) settle down and we’re not going to go grab them and ship them out of the country. I agree with that. I think he did the right thing on the strike in Syria."

Kasich has criticized Republican health care reform efforts. Of Trump, Kasich said, "He can say what he wants about the health bill but I don’t think he really is into the details of it, or his budget, for that matter."

Kasich faulted Trump for making "efforts at dividing or getting back into a campaign mode…at times."

"I want him to do well," Kasich said. "And doing well, I think it’s a matter of understanding the gravity of the office and working, despite people’s differences, to bring people together."