Donald Trump is inheriting a more powerful presidency than any of his predecessors. And if history is any guide, he will seek to expand the power of the office. But how will he do it? One clue lies in noticing how the personalities of the last two presidents were reflected in their techniques of expansion. Barack Obama’s administration took a very different route to its expansion of executive authority than did George W. Bush’s — and Trump’s will probably be different still.

The imperial presidency, as historian Arthur Schlesinger Jr. called it during the Nixon years, always had two faces. The president’s domestic empire grew out of the New Deal expansion of the welfare state, enhanced by regulatory agencies born in the 1960s and ’70s that gave the executive primary authority over the air we breathe and the food and drugs we ingest.

The president’s foreign empire emerged after the change in the U.S.’s global position post-World War II. The Cold War made the president for the first time the leader of the free world. And the president’s capacity to push the nuclear button and end life as we know it was a technological shift with major implications for executive power. It may or may not have changed the U.S. from a republic into a “thermonuclear monarchy,” as the literary theorist Elaine Scarry has argued, but it certainly made the declaration of war contemplated by the Constitution seem outdated.

Bush’s expansion reflected his personality, and the breakdown of the distinction between the foreign and domestic fronts after the Sept. 11 attacks.

Bush famously thought of himself as the “decider,” and his administration’s approach to executive power reflected that impulse. His lawyers loved to assert what they called inherent executive power — authority derived from a distinctive reading of Article II of the Constitution. This kind of power could be exercised by the president alone in defense of the nation, without asking anyone else in government.

It’s easy to see how attractive this “decider” vision must have been when security was the overarching and immediate priority. It’s appealing to think of the Constitution as adequate to the task of firm, fast, centralized decision-making.

This led the Bush administration to seize and detain people it considered terrorists, both abroad and in the U.S. It led to the prison at Guantanamo Bay, Cuba, and to waterboarding and war-crimes tribunals. It also authorized sweeping surveillance. If domestic laws seemed to prohibit some of these security measures, the Bush lawyers repeatedly (and secretly) argued that they were superseded by the Constitution.

These expansions characteristically took place at the intersection of foreign and domestic executive power: the new and ambiguous borderline created by the Sept. 11 attacks and the U.S. response. But Bush had relatively little interest in expanding classic domestic power through agencies. And his wars abroad were straightforwardly authorized by Congress.

Obama’s lawyers had in many cases spent years attacking the idea of inherent executive power, so their legal approach was totally different. Taking a cue from Supreme Court decisions mostly written by John Paul Stevens, they set out to maximize executive power in a new way — one that matched Obama’s legal training and technocratic, pragmatic, controlled temperament.

Instead of saying the president’s power was constitutionally inherent, the Obama lawyers systematically claimed that laws passed by Congress gave the president tremendous authority — authority that extended beyond what the president could exercise acting alone. Thus, indefinite detentions of terrorists were legal because Congress had authorized the use of military force, which necessarily included the right to take and hold prisoners of war for the length of hostilities.

The result was to maintain the president’s power to do essentially anything Bush had done, but to put the claim on the firmer legal footing of congressional authorization, rather than inherent authority.

The attractions of this interpretive approach — superficially modest but actually far-reaching — became clear when it came to the use of force abroad. Even though Congress did not expressly authorize the war against Islamic State, Obama’s lawyers said Congress could be understood to have done so by authorizing force against al-Qaeda and its affiliates in 2001, or maybe by authorizing war against Iraq.

It didn’t matter that Islamic State wasn’t al-Qaeda or that defending Iraq wasn’t the same as invading it. Congress had spoken, and the president had interpreted.

At home, the same interpretive authority enabled Obama’s executive order on immigration. Congress had given the executive the authority to deport, so he could legally prioritize whom to send home, and whom to keep in the U.S.

Trump’s character is more expansive and impulsive than those of his two immediate predecessors — and the personal stakes of the presidency are different for him. Expect that to be reflected in his power expansion.

In a sense, this expansion has begun even before he’s taken office, with his claim to the New York Times that “The law’s totally on my side, meaning, the president can’t have a conflict of interest.”

It’s true the federal conflict of interest laws don’t cover the president or vice president. But Trump, who has happily commented on the positive effect of the presidential election on his brand, surely means something more: He believes his personal and business conduct can’t really be separated.

Trump’s expansions are thus likely to take place in the personal sphere: where the president and the presidency come together.  This sphere will cut across the international and domestic realms, much like Trump’s businesses.

Trump will likely push the envelope of executive power by trying to influence the public by going around the press, and the press by appealing to the people. He will mix business, brand and governance — including in talks with foreign leaders, as in his chat with Nigel Farage about wind farms near his Scottish golf course.

On one level, these expansions seem more troubling for a democracy than Bush’s or Obama’s, because they blur the line between public and private. On another level, they may change the nature of executive power less, because they are more tied to the man than to the office.

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.