On election night, Donald Trump repeated the phrase: "Promises made, promises kept."

Now, Republicans have officially taken control of Congress and his "promises" are a whole lot easier to keep.

In Washington political parlance, it's called "a governing trifecta", when the president's party also controls both chambers of Congress - the House of Representatives and the Senate.

That control is what Donald Trump's Republican Party now has.

Single-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 roll around two years later.

Both Trump and Joe Biden enjoyed trifectas for their first two years in the White House, but they also saw that having such control is no guarantee a president can get their way.

In his first two years, Trump passed a signature tax bill - reducing corporate taxes from 35% to 21%, and cutting some taxes on individuals.

But with some members of his own party resistant to his surprise ascent to the top in 2016, he struggled with other aims.

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

In his first two years, when the Democrats controlled the House and the Senate, Biden succeeded in passing the American Rescue plan, the Investment and Jobs Act, and the Chips and Science Act. But he, too, had to significantly scale back his spending and investment plans - touted as the Build Back Better package - after opposition from one of his own senators.

A major impediment to total control for either party is that Senate bills require a three-fifths majority, or 60 votes, to bypass the filibuster, which enables senators to delay legislation by keeping debate open-ended. That means that when a party has a simple majority in the Senate, it needs to reach across the aisle to get a bill passed.

Even with a healthy majority in the Senate this time around, Trump will not have the magic 60 seats that would allow him to overcome opposition attempts to delay legislation.

And on Wednesday, Republicans in the Senate selected John Thune as their majority leader over Florida's Rick Scott, the clear favourite in the Trump camp, in a sign some lawmakers may be reasserting their independence (Trump did not officially endorse Scott).

That said, a trifecta, if astutely managed, does open the way for the possibility of major legislative initiatives.

Trump's power advantage could be key in pushing through his big promises such as the largest deportation of migrants in history, sweeping tariffs on foreign imports, and the rolling back of environmental protections.

Using legislation to achieve these ends will make such plans much harder to overturn in the courts - something Donald Trump was plagued by in his first term when he extensively used executive orders that were regularly and often successfully challenged.

The judicial landscape also has changed in Trump's favour.

The signature achievement of his first term was putting three conservatives on the Supreme Court - cementing a two-thirds majority for possibly decades to come.

He also named more than four dozen judges to the federal appeals courts, flipping several circuits to a more conservative bent.

The majority Republicans have in the Senate also provides a key advantage.

Trump will be able to get his nominees for administration posts approved more easily, something he struggled with back in 2017 when internal resistance to him in the Republican Party was still significant.

All this bodes for a busy and possibly turbulent next two years. But, as recent history indicates, these trifectas don't last all that long. The incoming administration will want to get a move on.