NEW YORK - President-elect Trump is set to take office under immense pressure to quickly deliver on a list of audacious campaign promises that served as the cornerstone of his bid to disrupt Washington and undo pieces of President Obama's agenda.
Some of Trump's most dramatic undertakings - such as canceling Obama's "illegal" executive actions - can be done in his first hours as president. Other priorities, such as repealing and replacing the Affordable Care Act or building a wall on the Mexican border, will require the approval of Congress, which will be controlled by Republicans but could still squabble over details. Others still could run into political or legal obstacles that may be difficult to overcome.
Two of Trump's ideas could probably be realized as early as his first day in office: scrapping executive orders issued by Obama - including those that shielded from deportation some immigrants who are here illegally - and appointing a special prosecutor to investigate vanquished Democratic opponent Hillary Clinton.
The former is a common tactic for new presidents whose predecessors belong to the opposing party.
The latter would be a political risk. By going after the opponent he just defeated, Trump could imperil his chances of broadening his appeal to the millions of Americans who did not vote for him.
"He certainly could do it, but it could have a major, devastating impact on her and would create a very bad precedent like we see in Third World countries," where election winners often imprison their rivals, said John Banzhaf III, professor of public interest law at George Washington University.
Repealing the ACA would take an act of Congress, as would levying some types of tariffs on corporations that move operations overseas, ending regulations that limit pollution and coal production, getting rid of gun-free school zones, and renegotiating the Iran nuclear deal. He would have the authority to renegotiate trade deals such as the North American Free Trade Agreement that he has long railed against - and to withdraw with six months' notice if he wished - but such a move could be catastrophic for stock markets and the economy.
Building a wall on the southern border would require Congress to commit millions of dollars to make it happen. Trump also has no power to force Mexico to pay for it, as he has repeatedly promised to do, although he could pressure the Mexican government with threats to limit trade or drug-related law enforcement activities.
Heavily surveilling mosques in America in the way Trump has advocated would require courts to reinterpret constitutional protections and rights. And if he wants to follow through with his proposed ban on most Muslims from entering the country - which he stopped talking about in the final months of the campaign even as it remained on his campaign website - would immediately be challenged in court as either unconstitutional or against current law, legal experts said.
But Trump would probably have the ability to ban a narrower group of Muslims living in certain parts of some countries controlled by Islamic State terrorists because the immigration statutes afford some discretion on national security grounds.
At his final rally in Michigan on Monday, Trump said he would put in place "the largest tax cut since Ronald Reagan" and offered less specific ideas such as eliminating "every unnecessary, job-killing regulation."
"Just think about what we can accomplish in the first 100 days of a Trump administration," he told the crowd.