President Trump this weekend mocked the academic record of a dead man:

Trump's ridicule of the late Arizona Sen. John McCain came during a weekend tweeting spree that was, even by the president's own very low standards, extraordinary for its sustained thin-skinned narcissism. He complained about a Saturday Night Live rerun, about a pair of insufficiently toadying Fox News anchors, and, of course, about Special Counsel Robert Mueller's investigation into his 2016 presidential campaign.

His criticism of McCain wasn't just incorrect — yes, McCain took the now-infamous Steele Dossier to the FBI, but he did it after Election Day — but extraordinarily petty. Even Sen. Lindsey Graham (R-S.C.), who has become one of Trump's most loyal sidekicks, felt compelled to issue a corrective of sorts.

There's plenty of evidence, however, that the GOP is still taking its social cues from the president. While Trump was fending off criticism for his mockery of McCain, the Republican Party's official Twitter account decided to celebrate St. Patrick's Day with this:

Forget making America great again. Whatever else their aims, Trump and the Republican Party are doing everything they can to help the country become trifling, picayune, and small.

It's true that our democratic politics can be ugly. Alexander Hamilton dueled with Aaron Burr, Grover Cleveland was exposed for fathering an illegitimate child, Richard Nixon was, well, Richard Nixon. The list of American leaders who behaved badly is long. But it's also true that we expect our presidents — despite being the products of such a rough-and-tumble process — to be bigger than all that. And if they can't, they should at least act bigger than that.

It's why FDR told us we have nothing to fear but fear itself. It's why JFK urged Americans to go to the moon and accept other big challenges "not because they are easy, but because they are hard." Heck, it is even why George W. Bush visited a mosque just days after 9/11 and told the country: "The face of terror is not the true faith of Islam."

Each man had moments in his presidency when he failed to exhibit much, or any, nobility. But each had moments when he stepped up, encouraged his fellow citizens to aim higher, work harder, and extend compassion to those around them. It's such a consistent pattern in the history of the Oval Office that many observers held out hope — long past the point of plausibility — that Trump would "pivot" into being presidential, to attempt to offer the country something bigger than his smallest self.

Instead, the president is frustratingly consistent: He seems always to take the lower road.

This is not the most consequential failing of Trump's presidency — those shortcomings are measured in separated families, emboldened tyrants, and inspired hate-mongers — but it is important nonetheless. Sen. Mitt Romney (R-Utah) probably overstated matters in January when he wrote that "the president shapes the public character of the nation." But can there be much doubt that the president — including the current one — at least has an influence? Trump offers an example of personal comportment no better than that of your average Twitter troll. The country is poorer for it.

As the Civil War drew to a close in 1865, President Lincoln delivered his second inaugural address. It was at once morally uncompromising — Lincoln suggested the war's brutal carnage was the country's payment for allowing slavery to thrive for more than two centuries — while also being surprisingly gentle in outlook: The war was necessary, he said, but healing would be, too.

Lincoln concluded his short speech with these remarkable words: "With malice toward none, with charity for all, with firmness in the right as God gives us to see the right, let us strive on to finish the work we are in, to bind up the nation's wounds, to care for him who shall have borne the battle and for his widow and his orphan, to do all which may achieve and cherish a just and lasting peace among ourselves and with all nations."

In the end, the words of Lincoln's address were inscribed on the walls of his memorial in Washington, D.C. — and the statue of Lincoln within the memorial looms much larger than the man himself ever did, the better to match the size of his character and place in our imagination. Trump should expect no such honor: He is our pettiest president.