NEW YORK (CBSNewYork) — A Twitter battle between President Donald Trump and Sen. Kirsten Gillibrand waged on Tuesday as he called her a “total flunky,” and she fired back saying he’s brought shame to the Oval Office.

“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,” Trump tweeted early Tuesday.

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The tweet came in response to the Democratic senator’s call for the president’s resignation over allegations of sexual assault.

At a press conference Tuesday morning the senator called the president’s tweet a “sexist smear attempt.”

“It’s part of the president’s effort at name calling and it’s not going to silence me. It’s intended to silence me. It’s not going to silence the women who have stood up against him directly and it’s not going to silence the millions of women out there who have been speaking out every day since his inauguration about things they disagree with,” Gillibrand said.

Gillibrand joined other Democrats on Monday who say Trump needs to step down after several women reiterated claims Trump sexually harassed them in the past.

President Trump did not explain what he meant when he tweeted “do anything” for campaign contributions.

White House Press Secretary Sarah Huckabee Sanders said she thinks Trump was “being very, very obvious” in his tweet and was “pointing out how the system functions as it is, that politicians beg for money.”

“There’s no way this is sexist at all,” Sanders said. “This isn’t new. This isn’t a new sentiment.”

Sanders said Trump has made similar comments about lawmakers from both parties.

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Sanders previously argued that Trump’s 2016 election victory answered groping allegations made during the campaign.

Gillibrand is calling for congressional hearings into the sexual allegations.

Senate Minority Leader Chuck Schumer called Trump’s tweet “unbecoming of a president.”

“Trump needs to cut it out with the tweeting, period,” Schumer wrote. “He should stop tweeting & start leading.”

Trump ignored questions about Gillibrand while talking about immigration Tuesday.

He said the broken immigration system is contributing to terrorism — including two recent attacks in New York. He wants Congress to fix loopholes.

“There have now been two terror attacks carried out by foreign nationals here on Green cards,” he said.

The president blamed terror attacks on a lax immigration system, which he said has contributed to two attacks in New York over the last six weeks.

“This first attacker came through visa lottery, the second by chain migration. We are going to end both of them,” he said.

The White House said the suspect in Monday’s attack immigrated to the country from Bangladesh on a family connection to a U.S. citizen, his uncle.

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“Hundreds of thousands of people come to this country every year based on this extended family migration category, and it is my view, it is this administration’s view, that that is not any way to run our immigration system,” U.S. Citizenship and Immigration Services, Frank Cissa said.