As the first major piece of legislation during President Trump's short tenure starts making its way through Congress, political observers and reporters are again buzzing about how Trump will use his “bully pulpit” to push through Republicans' effort to repeal and replace former President Obama's signature health care law.

The phrase, coined by Theodore Roosevelt and used to signal the power of the presidency to shape public opinion, seems to be getting extra attention in the early weeks of the Trump era. Not only does Trump have a massive social-media following and a fondness for campaign-style rallies -- which he's expected to use to sell the repeal-and-replace legislation to supporters in coming weeks -- but his use of social media to browbeat individual companies has some drawing parallels to his century-ago predecessor.

But the original meaning of the phrase, according to historians, is often misunderstood, and the "bully pulpit" may not be as powerful as it once was, or even seems. And while it may invite some comparisons between the 26th and 45th presidents — both brash, wealthy New Yorkers who had difficult relationships with their parties’ establishment — the similarities in their leadership are in other ways quite limited, historians say.

In the early 20th century, “bully” had an entirely different meaning, one that had nothing to do with throwing one’s weight around. “‘Bully’ just meant something that was really good, really positive,” said H.W. Brands, a historian at the University of Texas at Austin who has written books about many presidents, including one of Roosevelt. “He didn’t use it to threaten people with retribution. He didn’t promise to undertake reprisal against people who oppose him. Roosevelt would say ‘that was a bully good baseball game’ in very much the same way.”

Meanwhile, Roosevelt’s use of the phrase “bully pulpit” wasn’t necessarily about strong-arming lawmakers in Congress, but shaping public opinion by speaking directly to the American people who'd pressure lawmakers instead.

“When Roosevelt called the presidency the 'bully pulpit' he meant it was a really good platform from which to reach the people,” said Nicole Hemmer, an assistant professor of presidential studies at the University of Virginia's Miller Center. “It’s been reinterpreted in many ways as using public appearances as a cudgel to make other people do your will.”

Trump, of course, has found his own platform for speaking directly to the people, one that operates in 140 characters. Like other presidents who have mastered new forms of media — Roosevelt with mass circulation newspapers, Franklin Delano Roosevelt with radio, and Ronald Reagan with television — Trump has used social media to speak directly with the public, or at least with his supporters.

That concept was new in Roosevelt’s era, even if it isn't now. “Before Roosevelt, presidents, with some exceptions, sort of faded into the background,” Hemmer said. “Starting with Roosevelt you get this modern presidency where the president and his agenda come to define the politics of the time.”

In started partly out of necessity. Roosevelt, a progressive, was “deeply distrusted by the leaders of the Republican party,” Brands said, and found himself at odds with his party's leadership in Congress after suddenly becoming president following William McKinley's assassination in 1901. “He used to say anything the Constitution did not forbid him from doing, he thought was fair game,” Brands said. “He would put heat on the Republican leadership by going over their heads and speaking directly to the public."

Many will hear echoes of the current Republican president and his party in that — and many have drawn parallels between the two presidents, from their big personalities and distinctive physical traits to their populist appeal and fondness for executive power. But there are also many, many differences, both in substance -- Roosevelt believed in government as a force for public good and more regulation of big business, while Trump's chief strategist has vowed to fight for the "deconstruction of the administrative state" -- and in style.

Roosevelt, said Brands, was "thoroughly versed in the bills he was trying to promote" and "quite specific in explaining what he wanted to do," aiding him in shaping opinion. A progressive at the far left wing of his party, he was also adept at finding the middle ground.

Trump, meanwhile, has "not laid out in any kind of detail what he wants to see in terms of repeal and replacement of the Affordable Care Act, in terms of the infrastructure project, or tax reform," Brands says. "It probably reflects Trump's lesser command of the policy, but also Trump is not a gifted speaker." Roosevelt was a disciplined communicator, skilled at staying on message, even after famously being shot.

How much the "bully pulpit" really aids a president when it comes to passing legislation has come under question in more recent years. George Edwards, a professor at Texas A&M University who wrote On Deaf Ears: The Limits of the Bully Pulpit, has questioned the influence of presidential persuasion in empirical studies, telling the New Yorker in 2012 that Franklin Roosevelt "gave only two or three fireside chats a year, and rarely did he focus them on legislation under consideration in Congress."

Meanwhile, in a hyper-polarized environment, the power to persuade may matter much less than the advantage Trump already has: a majority in Congress. And it's become harder for presidents, no matter how many Twitter followers they may have, to set the public agenda in the way they did before the Internet and social media.

Trump may use Twitter to set the topic of the day, Hemmer said. "But his ability to define and shape and control that topic -- which is the ultimate effectiveness of the bully pulpit -- he really doesn’t have that. Whether that’s because he doesn’t have the discipline or because no one can control the message in this kind of fragmented media environment, I’m not sure. But he doesn’t seem to have the ability to really bring it home."

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