Greg Mankiw, an influential conservative economist and a former top economic adviser to President George W. Bush, said that he left the Republican Party because it has "become the Party of Trump."

"Too many Republicans in Congress are willing, in the interest of protecting their jobs, to overlook Trump's misdeeds," Mankiw, a Harvard professor, wrote Monday on his blog.

Mankiw said that he would vote in the Democratic presidential primary for a centrist candidate to prevent Elizabeth Warren or Bernie Sanders from getting the nomination.

He added that Warren or Sanders want to "move the country too far in the direction of heavy-handed state control" and therefore if they won the Democratic primary it would push "those in the center and center-right to hold their nose and vote for Trump's reelection."

Mankiw said he may rejoin the party when it returns to "having honorable leaders like Bush, McCain, and Romney."

The macroeconomics professor is known to be an advocate of free markets. He has written two very popular college-level economics textbooks and is frequently published in The New York Times, The Washington Post, and The Wall Street Journal. In addition to being the chairman of Bush's Council of Economic Advisers, Mankiw advised Mitt Romney during his presidential campaigns.

