President-elect Donald Trump has pledged to do everything from renegotiate US trade deals to forcing Mexico to pay for a wall along the US border.

But the president-elect's first change could happen on day one, if he fulfills an early campaign promise.

Last September, the then-Republican presidential frontrunner declared he would forego a presidential salary if elected, and would not seek outside contributions to his campaign.

"I won't take even one dollar. I'm totally giving up my salary if I become president," Trump said in a short video posted to his Twitter account as part of a question-and-answer session at Twitter's New York headquarters.

Of course, Trump walked back his promise to self-finance his entire campaign.

Though Trump pledged to self-fund the vast majority of his bid for president, he reversed his proposal and began raising money for himself and the Republican National Committee when he secured the Republican presidential nomination.

The Associated Press declared Trump the president-elect at 2:30 a.m. ET on Wednesday.

Trump’s victory was one of the most stunning political upsets in history. Clinton was strongly favored to emerge as the victor on Tuesday night, with some analysts estimating Trump’s odds of winning the election as low as 1%.