Krugman suggested he believes that the public-private co-investment strategy of Trump's proposed $550 billion infrastructure package would allow the president-elect to give favorable contracts to associates or even his own companies. Krugman wrote that Trump's family could take $10 billion "skimmed off the top" without anyone noticing.

"Expect to see lots of privatization and a general shift from transparent to murky so that favors can be traded," Krugman wrote.

Trump has already prompted questions about his business dealings and family as he transitions into the presidency. Presidents typically put their private business interests in a blind trust during their terms. Trump has said that his business interests would be shifted to his children.

Additionally, Krugman said the president-elect's foreign policy would be tilted toward authoritarian governments that could trade favors with Trump.

"And think about the pro-tyrant bias of foreign policy," Krugman wrote.

"Democratic regimes — say, in Europe — are by their own rules unable to offer de-facto personal bribes to the US president," he continued. "Putin's Russia or, for that matter, Xi's China, will be fine with sending huge business to the profiteer-in-chief. And that will cause a tilt of US policy toward authoritarian regimes."