Donald Trump is politically powerful, but he is not omnipotent, the BBC points out in its analysis.

On election night, Donald Trump repeated the phrase: “Promises are made, promises are kept.” Now, Republicans are officially in control of Congress, and his “promises” are much easier to keep.

In Washington political parlance, it’s called a trifecta when the president’s party also controls both houses of Congress – the House of Representatives and the Senate. That control is now held by Donald Trump’s Republican Party.

One-party control was once common, but in recent decades it has become rarer and shorter. Often, the party in power loses seats when midterm congressional elections are held about two years later.

Both Trump and Joe Biden enjoyed the trifecta of governance in their first two years in the White House, but they also saw that having such control is no guarantee that a president can do whatever he wants.

In his first two years, Trump passed an ambitious tax bill – cutting corporate taxes from 35% to 21% and some personal taxes as well. But with some members of his party resisting his surprise rise to power in 2016, he has had trouble achieving other goals.

His plan to repeal the Patient Protection and Affordable Care Act (known as Obamacare) failed when a senator from his own party, the iconic John McCain, refused to vote for it. He also failed to pass an infrastructure bill as promised.

In his first two years, when Democrats controlled the House and Senate, Biden succeeded in passing the “American bailout,” the Investments and Jobs Act, and the Semiconductor and Science Act. But he, too, had to significantly curtail his spending and investment plans – touted as the “Build Back Better” package – after opposition from one of his senators.

A major obstacle to absolute control for either party is that Senate bills require a three-fifths majority, or 60 votes, to bypass the so-called “filibuster,” which allows the minority party to block laws from passing. This means that when one party has a simple majority in the Senate, it must meet “with the opposite party” to pass a bill.

Even with a sufficient majority in the Senate this time, Trump will not have the “magic” 60 seats that would allow him to overcome opposition efforts to delay the legislation.

And on Wednesday, Senate Republicans chose John Thune as majority leader over Rick Scott of Florida, the clear favorite in the Trump camp, in a sign that some lawmakers are reasserting their independence from the president-elect (Trump has not formally endorsed Scott).

That said, a trifecta, if done carefully, paves the way for the possibility of major legislative initiatives.

Trump’s power advantage could be the key to fulfilling his big promises, such as the largest deportation of immigrants in history, sweeping tariffs on foreign imports and a rollback of environmental protections.

Using legislation to achieve these ends will make it much more difficult to overturn such plans in court – a scourge for Donald Trump in his first term, when he made extensive use of executive orders that were regularly and often successfully challenged.

The judicial landscape has also shifted in Trump’s favor.

The signature achievement of his first term was placing three conservatives on the Supreme Court—establishing a two-thirds majority probably for decades to come.

He also placed dozens of judges on federal appeals courts, tipping the judiciary toward a more conservative bent.

The Republican majority in the Senate also provides a key advantage.

Trump will be able to approve his cabinet nominees more easily, something he struggled with in 2017 when internal opposition to him was still significant.

All of this bodes well for a busy, and possibly tumultuous, next two years. But, as recent history shows, those trifectas don’t last that long. The new management will want to move on.