CHICAGO (CBS) — Illinois Sen. Tammy Duckworth blasted President Trump today over a controversial tweet about her Senate colleague, Sen. Kristin Gillibrand.

Gillibrand has called for Trump to resign or risk being at the center of an investigation for the multiple sex harassment allegations leveled against him.

The president this morning called Gillibrand a “lightweight” who “would do anything” for a campaign donation:

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

Duckworth called the president “Cadet Bone Spurs”–a reference to Trump’s medical reason for avoiding the Vietnam War. “Disparaging women doesn’t make you look stronger–it only reveals your weakness as a leader,” she said.

Then again, perhaps we shouldn’t be surprised when Cadet Bone Spurs, who has a documented history of “grabbing” women, fails to treat women professionally or appropriately — Tammy Duckworth (@SenDuckworth) December 12, 2017

Trump has a habit of using disparaging nicknames for his opponents on Twitter, from “Crooked Hillary” Clinton to “Pocahontas” for Sen. Elizabeth Warren.

At the White House press briefing today, spokeswoman Sarah Sanders denied the President was using any sexual innuendo when to said Gillibrand “would do anything” for money.

“Only if your mind is in the gutter,” she told reporters.

"Only if your mind is in the gutter," Sarah Sanders says of those who thought POTUS was suggesting something salacious by saying Gillibrand "would do anything" for campaign contributions. — Jake Tapper (@jaketapper) December 12, 2017

Gillibrand said she would not be silenced.

“It was a sexist smear attempting to silence my voice, and I will not be silenced on this issue,” she said.