President Trump repeatedly emphasized the importance of the first 100 days of his potential presidency while on the campaign trail. All of these clips were filmed between Oct. 24 and Nov. 6, 2016. (Gillian Brockell/The Washington Post)

On Friday morning, Donald Trump had something to say about his first 100 days. In a tweet, he wrote “no matter how much I accomplish during the ridiculous standard of the first 100 days, & it has been a lot (including S.C.), media will kill!”

That tweet, which appears to recognize his nomination of Neil M. Gorsuch to the Supreme Court, followed his claim last Tuesday in Kansas that “no administration has accomplished more in his first 90 days” — a statement historians quickly countered. He told Fox Business in an interview aired April 12 that “I don't think that there is a presidential period of time in the first 100 days where anyone has done nearly what we've been able to do.” Shortly before his election, the president sent out a “contract with the American voter” that detailed what he planned to pursue on his first day in office, as well as a "100-day action plan to Make America Great Again” with 10 legislative vows.

But most presidents shy away from spotlighting the three-month measure, historians say, whether to keep from setting impossible deadlines, resist raising expectations too high for their leadership or because they weren't seeking to make much change.

“I cannot think of a president or administration that has taken seriously the 100 days,” says H.W. Brands, a historian at the University of Texas at Austin who has written biographies of several presidents, including Franklin Delano Roosevelt, whose astonishingly productive early period amid failing banks, a Great Depression and an agricultural crisis in the 1930s left us with the memorable — if artificial — yardstick for measuring presidents.

Ronald Reagan, Brands notes, “did not say 'I'm going to do this on Day One,'" even if he made a lot of promises. “He said 'we're going to do this,' but he didn't go out of his way to set deadlines.” George H.W. Bush, Reagan's former vice president, wasn't looking for a shake-up, and his son, George W. Bush, said “the only thing I know to do is just to give it my all” when asked to evaluate his tenure during the same period. Barack Obama, of course, made grand promises on the campaign trail for what he wanted to achieve, but also said he wanted to be judged by his first 1,000 days rather than his first 100.

That echoed another president who'd cautioned the same thing. Barbara Perry, director of presidential studies at the University of Virginia's Miller Center, said one of the few presidents who's spoken directly about the 100-day milestone is John F. Kennedy, who raised it in his inaugural address — though he did so to downplay it. After listing a number of lofty aims, “all this will not be finished in the first one hundred days. Nor will it be finished in the first one thousand days, nor in the life of this administration, nor even perhaps in our lifetime on this planet. But let us begin.”

Of course, there have been presidents besides Trump who have promised the moon and invited the inevitable comparison. Bill Clinton dramatically vowed “an explosive 100-day action period” that would be “the most productive period in modern history” during the campaign, setting himself up for particular scrutiny. Yet following a stumbling start that saw difficulties with his attorney general nominations and a Republican filibuster of his jobs stimulus package, Clinton also said a few months in that “there's a lot I have to learn in this town.”

Trump, too, campaigned on the long list of things he would pursue early on in his presidency — and many on day one, not just by day 100. That's driven expectations for him and his staff. “He wants that because it looks like he's doing something,” she said. “This approach to how he's run his office — his reality TV persona — is don't just stand there, 'do something.' Most presidents are realists. But this is a man who constantly talks in superlatives.”

Brands said that even the president who most modeled himself after FDR, Lyndon Johnson, “understood there was no huge hurry.” After his landslide victory in 1964, Johnson “didn't feel he was under any compulsion. ... He brought his team together and said 'we’ve probably got 18 months, or two years. If you want to do big things, you’re going to have to be popular.' He wasn’t talking about 100 days.”

Casey Dominguez, a political scientist at University of California San Diego, has studied presidential “honeymoons” and found that it is indeed true that presidents tend have a little more success in their first three months. But that has historically been driven by the opposition party being willing to give a little more when a new president is elected, particularly with a mandate.

She notes, however, that not only is it “absurd” to hold presidents up to the standard of Roosevelt, but that even measuring a president's legislative activity misses something. “The thing that’s missed, generally, is we shouldn’t really even expect the president to be a legislative leader,” she says. “It's not his constitutional responsibility. It can be a focal point, but his own party in Congress doesn’t need him in order to legislate.”

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