US President Donald Trump on Thursday reacted to House Speaker Nancy Pelosi’s comment on the 25th amendment to the US Constitution, which lays out succession if the president is incapacitated or deemed unable to carry out his duties.

“Crazy Nancy is the one who should be under observation. They don’t call her Crazy for nothing!” Trump wrote on Twitter.

His reaction came after House Speaker Nancy Pelosi, in a press conference on Friday said she and the other Democrats would introduce a measure related to the US Constitution’s 25th Amendment, which allows for the vice president to take over, if it’s determined that the president “is unable” to fulfill his duties.

Also read: Nancy Pelosi announces plan to probe Donald Trump’s fitness for office

Republican Mark Green also slammed Pelosi saying she is using the 25th amendment as a weapon like she did with the impeachment.

“I wouldn’t put it past @SpeakerPelosi to stage a coup.

She has already weaponized impeachment, what’s to keep her from weaponizing the 25th amendment?

We need a new Speaker!,” he tweeted.

Pelosi’s office said Friday’s bill would “help ensure effective and uninterrupted leadership in the highest office in the executive branch of government.”

The move comes at a moment of crisis in the White House, with Trump being treated for a COVID-19 infection that sent him to the hospital for three nights.

However, her action is unlikely to bring about a transition of power in the White House, as Vice President Mike Pence, a Trump loyalist, would be required to sign off on such a declaration.