Former Republican New Jersey Gov. Christine Todd Whitman said President Donald Trump is "clearly unfit to remain in office" and called for him to step down Sunday, in a lengthy Los Angeles Times op-ed.

Todd Whitman, who also led the EPA during President George W. Bush's first term, said Trump's "disgraceful performance" before Russian leader Vladimir Putin during their controversial summit last week in Finland helped her come to such a conclusion.

"I am a lifelong Republican. I have campaigned and won as a member of the party and I have served more than one Republican president," Todd Whitman, who also worked in the Nixon White House, said.

Todd Whitman said she recalled her fellow Republicans criticized President Obama for his "engagement strategy" with Putin and are now engaging in "willful ignorance of the damage Trump is doing both domestically and internationally."

'Making America 1929 Again': GOP Sen. Sasse Rips Trump on Tariffs, Planned Farmer 'Bailout'

'This Girl or Whatever She Is': DeSantis Draws Response After Calling Out Dem Socialist

She said Trump has a "sycophantic relationship" with the ex-KGB agent and that such a detente is "unsurprising."

"Trump's avowed respect for the word of a dictator who has spent decades undermining the U.S. and its allies is utterly dangerous," Todd Whitman said.

She said Republican officeholders should come together and help the country by calling on Trump to step down.

She also called for Congress to protect the viability of the Mueller probe.

"Invoking the need to choose country over party is an overused trope. But it is essential now," Todd Whitman said.

Todd Whitman served as governor from 1994 to 2001, when she resigned to serve in the White House.

WATCH: Trump Brings 94-Year-Old Veteran on Stage, Invites Him to Oval Office

'He Wants Heads to Explode': Baier Says Trump Is Trolling Media, Left With Tweets