The power of the presidency looks much grander from the perspective of the campaign trail than it does from the White House. Once a president is in office, he is confronted with the power of the other branches of government, Congress and the courts as well as the multitude of institutions and political actors, from reporters to grass-roots activists, who can cause problems for any administration.

Historically, we see presidents adjust to the realities of governing. This has been a truism in American politics, often to the chagrin of campaign supporters who believe that the president, by adjusting his agenda, is abandoning promises and core principles. But the best presidents often learn that it is only through compromise, pragmatic adjustment and flexibility that one can be successful in our system of separated power.

The question is whether President Donald Trump will make this shift.

There are a number of times when new presidents, who tend to be bold and ambitious, are forced to make adjustments once their term starts. One of the most important reasons has been that elections are not really mandates in the United States (so the losers still hold on to some sources of power).

President John F. Kennedy entered office promising a new era, but much of his domestic agenda remained dormant throughout his term given the power of conservative Southern Democrats in Congress. "The fact is I think the Congress looks more powerful sitting here than it did when I was there in the Congress," Kennedy said in 1962.

Despite all the drama of the 1980 election, President Ronald Reagan still had to contend with a Democratic House throughout his presidency. Every time he tried to move domestic policy to the right, cutting welfare and dismantling programs, he encountered resistant majorities that forced him to curtail his ambition.

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President Bill Clinton moved to the center as congressional Republicans regained control of Congress in 1994.

President Barack Obama promised in 2008 to redirect our national security programs fundamentally, but he ended up backing away from closing Guantanamo, escalating our military operations through drone strikes and leaving much of the post-9/11 counterterrorism program in place.

Circumstances also can change dramatically, and presidents have to change with them. Franklin D. Roosevelt campaigned promising to be a fiscal conservative and keep federal budgets low. But the severity of the Great Depression and the need to boost consumer demand gradually led him to loosen some of those ambitious and open up the nation's purse strings so to pump prime the markets.

Richard Nixon promised in 1968 to bring an end to the Vietnam War. His ability to do so was limited. Although he would start to pull American forces out of the conflict, leaving the South Vietnamese to do more of the fighting themselves, he continued a brutal and massive bombing campaign against the North Vietnamese that would lead to a national outcry against his duplicity.

George W. Bush campaigned by famously lashing out against Clinton's proclivity for nation-building and promised to limit US involvement in the world. But then the horrors of 9/11 took place. Bush responded by vastly expanding the national security apparatus and involving US military forces in two major military conflicts.

Presidents also change because they learn on the job. The wisdom of governance comes from having a full sense of the issues facing the nation and a better grasp of intelligence -- both national security and domestic challenges -- where they move away from some of the bluster that was used when campaigning.

Jimmy Carter promised to transform the way that American politics worked but in the end had to work with congressional Democrats who were essential to any legislative victories. George H.W Bush swore that he would never raise taxes in 1988. But when push came to shove and he was dealing with the urgent need to reduce the deficit from the Oval Office, he conceded, angering the right and working with Democrats on a package that raised revenue. Though they were one-term presidents, their respective accomplishments on the Camp David peace accord and deficit reduction are considered impressive.

There are a few signs that Trump might be shifting on some issues . Scratch beneath the surface of the Twitter blizzard and we have seen him back away from Taiwan, send mixed signals on Israeli settlements and offer some indications that it won't be possible to dismantle the Iran nuclear deal.

Still he has a long way to go. Overall, he is sticking to the script from the campaign trail and insisting he won't move away from his core promises. This is what his supporters want. He promised to stop the flow of refugees and that is what he is trying to do. The refusal by an appellate court to reinstate the ban on refugees was a blow to the administration's policy agenda. Trump was checked, and he is being forced to come up with a game plan for responding. But he hasn't backed off his message that refugees pose a threat to US national security, even though the evidence suggests otherwise.

He said he would build a wall on the Mexico border, and he is trying to find money to do just that. When Republicans started warning that people were dependent on the Affordable Care Act, he has insisted that even if it might take longer than he thought, the ACA will go.

Trump has no interest in changing. As one article in Politico concluded, "In interviews, nearly two dozen people who've spent time with Trump in the three weeks since his inauguration said that his mood has careened between surprise and anger as he's faced the predictable realities of governing."

While this might play extremely well with his base of support, it is a model of presidential leadership that is bound to run into trouble.

The courts have already offered Trump the first check and balance. Mass protests have also greeted his decisions and presidency, generating a formidable opposition movement that shows no signs of abating. Congressional Democrats are using what power they have to slow down and delay him. The question is whether and when some Republicans might start to take a stand against Trump, not just with their words but with their votes.

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Lyndon Johnson always used to talk about the limits of presidential power. From his long time on Capitol Hill, he felt that Congress would get the best of any president at some point. In fact, Johnson was a president who paid a steep price for refusing to change.

Although he campaigned in 1964 promising to be tough against communism, without going as far as his opponent Barry Goldwater, he refused to change course when officials such as Sen. Richard Russell and Vice President Hubert Humphrey warned him in 1965 that the Vietnam War was a mistake. Instead he got the nation deeper and deeper into a quagmire that eventually undid him and had disastrous consequences.

If Trump refuses to adjust and recalibrate on some key issues, there will be a tipping point where he can't overcome the institutional limits of his power, particularly given his weak standing in the national polls. When that point comes remains unclear, but history does suggest that even the most imperial presidency, such as that of Nixon, can ultimately be stopped.