Back in February 2016, Andrew Wheeler, a prominent coal lobbyist, was working as a volunteer consultant for energy and environmental policy for the campaign of Sen. Marco Rubio (R-Fla.).

Ahead of the 11-state “Super Tuesday” primary vote March 1, Rubio was in a crowded race for the Republican Party’s presidential nomination. The biggest hurdle between Rubio and a spot on the general election ticket was the seemingly long-shot candidacy of political newbie Donald Trump.

Friends of Wheeler — who has spent nearly a decade lobbying for energy companies such as coal giant Murray Energy — encouraged him to write a post on his personal Facebook account the day before Super Tuesday pleading with those considering voting for Trump to reconsider.

“I’m from Ohio and have a lot of friends in Ohio who vote on Super Tuesday,” Wheeler told The Washington Post on Friday, “and a couple of friends had said to me when I was working for Rubio that I ought to post something about the campaign.”

In his six-point critique on Facebook, Wheeler laid out a skepticism of Trump’s character, business acumen and viability as a general-election candidate that many elected GOP officials and “establishment” Republicans shared at the time.

Trump was a “bully,” Wheeler wrote in the since-deleted Facebook post obtained by The Post, one who “hasn’t been that successful” in business and who “has more baggage then all of the other Republican candidates combined.” Wheeler added that Trump “has demonstrated through the debates and interviews that he doesn’t understand how the government works.”

But what truly precluded Trump from becoming president, in Wheeler’s view at the time, was his propensity to bully. “This alone should disqualify him from the White House,” Wheeler wrote.

Now more than a year and a half later, that White House, now occupied by President Trump, nominated Wheeler this week to be deputy administrator of the Environmental Protection Agency.

In an interview with The Post, Wheeler explained how he went from critic of Trump to a volunteer for the eventual GOP nominee to, ultimately, Trump’s choice for the No. 2 position at the EPA — a nomination that has engendered some of the harshest condemnation of the administration from environmentalists to date.

If confirmed by the Senate, Wheeler will join Energy Secretary Rick Perry, who once called Trump “a cancer on conservatism,” and Housing and Urban Development Secretary Ben Carson, who once questioned Trump’s religious faith, among several high-level administration officials who had pilloried Trump during the 2016 election.

“I was just looking at the debates and what I saw on the news, and I hadn’t focused on what he was saying,” Wheeler said this week of Trump, “and when I started looking into what he was saying and what his campaign and what his candidacy was about, I was fully on board.”

Having worked in Washington since the early 1990s — starting as a career employee at the EPA in the George H.W. Bush administration before working on Capitol Hill — Wheeler fits the bill of an establishment GOPer.

For more than a decade, Wheeler worked in various roles for Republicans on the Senate Environment and Public Works Committee, which oversees the EPA. If confirmed by the Senate, Wheeler will become the latest former staffer for Sen. James M. Inhofe (R-Okla.), the committee’s former chairman, to join the EPA, now being run by another Oklahoma Republican, Scott Pruitt.

Similar to Pruitt, Inhofe is known for questioning the scientific consensus that human activity is warming the planet. Once famously tossing a snowball on the Senate floor, Inhofe has called climate change “the greatest hoax” ever foisted on U.S. citizens.

This week, environmental groups again harshly criticized Trump for nominating Wheeler. Citing his time in Inhofe’s office, Melinda Pierce, legislative director at the Sierra Club, said, “There actually could not have been a worse choice for this highly influential position.”

In early 2016, as Trump began winning presidential primaries and accumulating delegates, Wheeler said he wasn’t sure where Trump stood on energy and environmental issues. “I hadn’t heard him speak,” Wheeler explained this week. “I hadn’t really looked at what he was saying.”

Indeed, in that February Facebook post, he wrote: “no one really knows what his political beliefs are, he has donated to both parties over the years and to people with completely opposite views.” He added that Trump “has given no details, no details at all, about what he would do or how he would do it.”

Like other Republicans once apprehensive of Trump, Wheeler changed his tune once Trump articulated an energy and environmental platform — and once it became increasingly clear Trump would win the GOP nomination.

About three months after picking up more delegates than any other GOP candidate on Super Tuesday, Trump gave a major energy-policy speech in North Dakota, where for the first time Trump laid out his “energy dominance” agenda emphasizing the development of domestic fossil-fuel resources.

In that May 2016 speech, Trump promised to “cancel” the Paris climate accord and undo Obama administration efforts to give the EPA broader authority to regulate water pollution, known as the “Waters of the United States” or WOTUS, rule.

“I think the federal government should get out of the way,” Trump told the crowd. “We have so much potential energy people wouldn’t even believe it.”

“A lot of my friends in the Republican energy and environment field here in D.C. were impressed with that speech,” Wheeler said this week.

Wheeler said he was finally swayed in June when Trump spoke at a closed-door fundraising dinner in Wheeling, W.Va., that Robert Murray, chief executive of Murray Energy, hosted and Wheeler attended. After leaving Capitol Hill, Wheeler worked as an energy consultant and lobbyist for Faegre Baker Daniels Consulting, where his clients have included Murray Energy in 2009.

“It was about a 40-minute energy speech that he gave,” Wheeler told The Post. “He didn’t use notes. He didn’t use a teleprompter. I really thought it was the most comprehensive energy speech by a presidential candidate I had ever heard.” After that, Wheeler said he joined the Trump campaign as one of two volunteer energy and environmental policy consultants. “I didn’t talk to a lot of people about being on the campaigns,” Wheeler said.

Already, Trump has made good on many of those campaign promises, to the lament of environmentalists and their Democratic allies. In June, the Trump administration announced its intent to withdraw the United States from the Paris agreement and to revoke the WOTUS rule.

As Wheeler prepares to join the EPA, the agency is reviewing pollution rules that the Obama administration placed on coal-fired power plants that, in turn, affect coal suppliers such as Murray Energy. They include rules regulating how much mercury coal plants can emit into the air and how a byproduct of those power plants called coal ash is disposed of. Senate Democrats will probably ask Wheeler if he will recuse himself from working on any EPA rules he had lobbied on in the past.

Watching from afar, Wheeler said he is happy with what he has seen so far. “I’ve really liked what I’ve heard Administrator Pruitt talk about,” Wheeler said, “getting back to the core mission of the agency.”