A Bay Area congresswoman is calling for President Donald Trump to be removed from the presidency under a never-before-used constitutional provision.

Rep. Jackie Speier, D-San Mateo, on Tuesday became the first member of Congress to say that Trump should be removed from office with the 25th Amendment, following his latest comments blaming “many sides” for violence after white nationalist protests in Charlottesville, Virginia.

“POTUS is showing signs of erratic behavior and mental instability that place the country in grave danger,” Speier tweeted Tuesday evening. “Time to invoke the 25th Amendment.”

POTUS is showing signs of erratic behavior and mental instability that place the country in grave danger. Time to invoke the 25th Amendment. — Jackie Speier (@RepSpeier) August 16, 2017

The fourth section of the 25th Amendment, which has never been invoked, states that the vice president and a majority of the Cabinet can temporarily remove the president from office by declaring him or her “unable to discharge the powers and duties of his office” in a letter to Congress. The vice president would then become the acting president.

If the president objects to his or her removal, the debate goes to Congress. A two-thirds majority vote in both houses of Congress is required to keep the president from returning to office.

But there’s been no sign — publicly, at least — that Vice President Mike Pence or the members of Trump’s Cabinet are considering taking action to remove him.

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In an interview with the Bay Area News Group, Speier said on Wednesday said she’d been thinking about the 25th Amendment for a long time, as she met with foreign dignitaries who voiced worries about Trump’s policies and personal stability. But “the tipping point” leading to her calling for his removal, she said, came in the last week or so.

“It was the combination of both his belligerence and hatred that he exuded relative to Charlottesville and his taunting of Kim Jong Un on North Korea, his willingness to send troops into Venezuela,” she said. “I’m very fearful right now.”

On his impromptu news conference inside New York’s Trump Tower on Tuesday, “It wasn’t just what he said; it was how he said it,” she said. “For him to have his finger on a button that could put us into mutual annihilation is not something I want to even contemplate.”

Some seasoned political observers, however, threw cold water on the prospect.

Jack Pitney, a professor of government at Claremont McKenna College, said the half-century-old amendment was designed for presidents in a coma or suffering from dementia or another disability, not those who “made extremely bad statements and extremely bad policy decisions.”

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“It’s an extremely remote possibility, to put it mildly,” Pitney said. “It’s hard to imagine his hand-picked Cabinet voting to oust him.”

But Speier argued that the possibility was “conceivable,” especially if Trump continued to publicly attack his fellow Republicans.

After the president’s comments Tuesday, there were growing calls for Trump to be removed from office. Rep. Gwen Moore, D-Wisconsin, said Tuesday that Trump should be impeached, joining a handful of members of Congress who’ve done so.

But impeachment isn’t a fast enough process, Speier argued, suggesting that the Republican majorities in both houses of Congress made it unrealistic as well.

Speier also quoted from Voltaire in a tweet: “Those who can make you believe absurdities, can make you commit atrocities.”

"Those who can make you believe absurdities, can make you commit atrocities." -Voltaire — Jackie Speier (@RepSpeier) August 16, 2017

Though not committing to an immediate attempt to remove Trump from office, Rep. Eric Swalwell told East Bay two Rotary clubs Wednesday that he supports the basic idea, perhaps via the 25th Amendment.

“It’s time for Democrats and Republicans to recognize that (Trump) can’t lead us,” said Swalwell, D-Pleasanton, who called the president “unfocused and unstable.”

Staff writer Sam Richards contributed to this report.