New York Sen. Kirsten Gillibrand called on President Trump to "immediately resign" yesterday, prompting a disparaging Twitter response from POTUS this morning:

Lightweight Senator Kirsten Gillibrand, a total flunky for Chuck Schumer and someone who would come to my office “begging” for campaign contributions not so long ago (and would do anything for them), is now in the ring fighting against Trump. Very disloyal to Bill & Crooked-USED!— Donald J. Trump (@realDonaldTrump) December 12, 2017

Gillibrand fired back with a tweet of her own, stating that Trump had brought "unfitness and shame" to his office:

You cannot silence me or the millions of women who have gotten off the sidelines to speak out about the unfitness and shame you have brought to the Oval Office. https://t.co/UbQZqubXZv— Kirsten Gillibrand (@SenGillibrand) December 12, 2017