In deciding to pull out of the global climate change accord, President Donald Trump seems to be calculating that he can win the White House the same way twice.

His lengthy — and disputed — economic and foreign policy explanations Thursday for ceding U.S. leadership on the issue were cast in terms that aimed to please his 2016 voters, those who were older, whiter and more rural than the nation as a whole. Their shared America leans toward defiant and aggrieved, yearning for the way things used to be, and seeing a future threatened by opponents domestic and foreign.

The president’s climate change decision was greeted with applause in his strongholds in places such as western Pennsylvania and West Virginia, whose economies have long been dependent on fossil fuels, primarily coal, that would be restricted by the Paris agreements’ terms for reducing emissions.

Yet Trump’s base is not a growing slice of the electorate. And his action likely further alienated younger, suburban and more educated voters among whom his support was weakest — a matter of increasingly open concern for many Republicans.

Indeed, the climate issue, although not a top one for most voters, is seen by both parties as a way to rally their core supporters. That and the extended timeline for withdrawal from the agreement virtually guarantees the issue will be fought over in the next presidential contest.

By all signs, Trump voters’ unlikely connection with a self-proclaimed billionaire from Manhattan has been emotional and, so far, lasting. Still, anticipating a second victory in 2020 via the same electoral path is risky, even if not impossible.

Trump won the presidency with only 46 percent of the vote, but that minority share was clustered in all the right places, giving him once-Democratic states such as Wisconsin, Pennsylvania and Florida for an Electoral College majority. As his hypothetical campaign positions become ever more real, however, Trump’s challenge is maintaining those voters — and adding to them.

Already he faces a threat of political fallout from the health care plan he is championing.

As a candidate, Trump promised to replace Obamacare with coverage that was better, cheaper and available to all regardless of income. But the House Republican health care plan he backs would drive more than 20 million Americans off the insurance rolls and hike costs for many others, according to the independent Congressional Budget Office. It found that the most vulnerable would be older and poorer Americans, including many who sided with Trump.

Thursday’s move could add to the political challenges, making Trump vulnerable particularly in states such as Florida, where residents already are feeling the effects of climate change as rising sea levels cause flooding.

Trump may have been keeping a campaign promise by pulling out of the agreement, but he also effectively took on responsibility for such negative outcomes from what he has called “a hoax.”

Rep. Carlos Curbelo, a Republican representing Key West and the southern end of Florida’s peninsula, issued a warning Thursday about Trump’s decision: “Down here in south Florida we understand that the environment and the economy are one and the same.”

Any re-election campaign will be a referendum on Trump himself. But so far, he has seemed to disregard the narrowness of his path to the presidency the first time, or the odds that he would be as lucky in drawing a flawed opponent next time.

Trump last year highlighted some moderate positions that seemed to open the possibility of attracting a broader range of voters, including support for a massive infrastructure program and a defense of some of Planned Parenthood’s work. But as president, he has hewed to the sharply conservative views of his loyalists.

His continued allegiance to them was evident in a closing line in his climate change speech intended as a paean to the old industrial titans of the Midwest and Northeast.

“It is time to put Youngstown, Ohio; Detroit, Michigan; and Pittsburgh, Pennsylvania — along with many, many other locations within our great country — before Paris, France,” Trump said, in what was his second shout-out to Pittsburgh in a few minutes’ time.

Strictly speaking, the line represented a sleight of hand. The climate deal was reached in Paris — allowing Trump to play to the recurring disdain among conservatives for the perceived elitism of France and, more broadly, to anti-globalism — but it was joined by every nation except Syria and Nicaragua. And the cities that Trump mentioned weren’t ones that he did particularly well in. He was swamped by Democratic nominee Hillary Clinton in Pittsburgh and Detroit, and lost more narrowly in Youngstown.

But as a metaphor for his campaign approach to troubled areas of the country, the line reflected what worked well for Trump in 2016 and helped to secure his hold on his voters.

Indeed, Thursday’s speech thrummed with campaign themes.

If his inaugural address in January blamed domestic elites for “carnage” in America, Thursday’s remarks represented the international parallel, in which Trump described a world in which foreigners “laughed at” America and threatened the country with “lost jobs, closed factories,” billions in spending and higher energy costs.

“They don’t put America first. I do, and I always will,” he said. Twice he expressed his “love” for American workers.

The same elites who castigated Trump last year — Democrats, establishment Republicans and intellectuals, and some business leaders — quickly criticized his climate decision, no doubt only tightening support among his loyalists.

There was, however, a subtle signal of concern. Trump made a point of saying that “one by one, we are keeping the promises I made to the American people during my campaign for president.”

Perhaps to buttress his supporters, Trump made another promise to them on Thursday.

“Believe me, we’ve just begun,” he said. “The fruits of our labor will be seen very shortly, even more so.”