"I will keep you in suspense," he said at the time.
Now, as the nation gears up to decide on Trump's reelection, the question of whether he would abide by an unfavorable result has again become acute, with House Speaker Nancy Pelosi, warning that Democrats must win overwhelmingly to ensure he walks away from the White House. A CNN poll last week found that a handful of Democratic candidates would beat Trump in a head-to-head contest. Meanwhile, the president has been lashing out at former vice president Joe Biden, who has polled as a top contender since entering the race last month.
The emergence of these battle lines was the context for Trump's weekend decision to broadcast the idea that he is owed presidential overtime. His claim is that the first two years of his presidency, which he also says were the most successful in history, were denied to him by a Democratic-led putsch, in the form of the investigation into Russian interference in the 2016 election. The probe was led by special counsel Robert Mueller, a Republican, who was named by another Republican, Deputy Attorney General Rod Rosenstein.
Trump got the idea from Falwell, who is an embodiment of the unlikely alliance between evangelical Christians and a thrice-married reality television personality who has appeared on the cover of Playboy magazine. Falwell took to Twitter on Saturday to celebrate the "best week ever" for the 45th president, echoing Trump's misleading characterization of the findings of Mueller's probe and touting robust economic performance.
"I now support reparations," he declared, adopting the language of Democrats discussing what is owed to historically oppressed minority groups. The evangelical leader argued that Trump should have two years added to his first term "as pay back for time stolen by this corrupt failed coup."
Trump retweeted Falwell's assertion to his 60 million followers on Sunday. Then, he made the case for himself.
In a pair of tweets - reposted Sunday night to correct a spelling error in his earlier pronouncement - the president said two years of his presidency had been squandered by the "Collusion Delusion." The rhyming catchphrase is his name for the probe into Russian election interference and the quest to discover whether members of his campaign team worked to enable foreign meddling and whether he acted unlawfully to obstruct the investigation. He also repeated his denouncement of the inquiry as a "Witch Hunt," even though he also claims falsely that it exonerated him.
Addressing constitutional limits on his time in office at a rally last month in Green Bay, Wisconsin, Trump told his supporters, "I promise at the end of six years, I'll be very happy." He ridiculed those warning that he would not step aside as "sick people."
Among those who have sounded the alarm is Michael Cohen, the president's former attorney and fixer, who is reporting to federal prison on Monday. In testimony before the House Oversight Committee in February, Cohen said part of his motivation for laying bare his dealings with Trump was his concern that his former boss would not settle for being a one-term president.
"I fear that if he loses the election in 2020, that there will never be a peaceful transition of power," Cohen said. "And this is why I agreed to appear before you today."
Legal experts were divided about the significance of the president's new complaint that he has been denied his due time in power.
"He doesn't mean anything by it," said Michael McConnell, a former federal judge who now directs the Stanford Constitutional Law Center.
McConnell, who was named to the federal bench in 2001 by President George W. Bush, dismissed the tweets as "bluster."
"If there were the remotest chance he were serious, and had power to put his words into effect, I might be concerned," he said. "But he is not serious, and he could not do anything about it even if he were serious."
But Jon Michaels, a law professor at the University of California, Los Angeles, said he took Trump at his word.
"I don't take this lightly because there's been a persistent campaign by this administration to undermine the rule of law in any number of respects, from not accepting the considered findings of judges because of their nationality or purported nationality to calling judges 'so-called judges' or 'Obama judges,'" Michaels said. "It's disconcerting."
Whether Trump means what he says, his protest "paves the way for future occasions to disregard or dispute the legitimacy of an election," the constitutional law scholar warned.
He also noted that some of Trump's followers on social media may be learning the rules and requirements of democracy from their president's utterances on Twitter. What some see as bombast, others may view as "an alternative trajectory for how this could all play out, departing from the basic tenets of our system."
There is no such thing as purloined years of a presidency, Michaels said, and the idea of a two-year extension is plainly unconstitutional.
"It's not like soccer where there's a penalty time, so they just add a couple minutes to the end of the game or the half," he said.
Unlike in a parliamentary system, where votes of no confidence are possible and the government enjoys leeway to call early elections, the constitution is explicit about the regularity of elections.
Certain assumptions about the electoral system are in fact coming under question, Michaels noted, including the value of the electoral college. But these discussions presume the need for constitutional revision, he said.
Trump is hardly the only president who has confronted the limits of his tenure. Most recently, President Barack Obama was asked by wistful supporters in the twilight of his second term to stay for a third, which is proscribed by the 22nd Amendment.
"Four more years," they chanted during his farewell address in Chicago in January 2017.
"I can't do that," he told them.
