"Ridiculous": Biden hits back at Trump over autopen investigation

• "This is nothing more than a distraction by Donald Trump and Congressional Republicans who are working to push disastrous legislation that would cut essential programs like Medicaid and raise costs on American families, all to pay for tax breaks for the ultra-wealthy and big corporations," he added in the emailed statement.

The big picture: Trump directed the counsel to the president, in consultation with Attorney General Pam Bondi and other officials, to investigate "whether certain individuals conspired to deceive the public about Biden's mental state and unconstitutionally exercise the authorities and responsibilities of the President," per the order.

• The investigation will center on Biden's use of the autopen, which Trump raised concerns about last month.

Zoom out: Biden has faced intensifying questions about his health during his presidency in the weeks since he was diagnosed with Stage 4 prostate cancer and following the release of the book "Original Sin," by Alex Thompson and Jake Tapper, about his administration.

Go deeper: New Book: Biden Cabinet members worried about his capacity in a crisis

Editor's note: This article has been updated with new details throughout.