The Fix's Callum Borchers explains the years-long feud between President Trump and the hosts of MSNBC's "Morning Joe." (Peter Stevenson/The Washington Post)

President Trump lashed out at the hosts of MSNBC's “Morning Joe” in two vicious tweets Thursday morning, calling Mika Brzezinski “low I.Q. Crazy Mika” and claiming she had a facelift late last year.

Trump also called Joe Scarborough “Psycho Joe” and said the hosts came to Mar-a-Lago — his private club in Palm Beach, Fla. — three nights in a row around New Year's Eve “and insisted on joining me.” He claimed that Brzezinski “was bleeding badly from a facelift” at the time and that, “I said no!”

Brzezinski and Scarborough were both spotted at Trump's New Year's Eve party, according to pool reports at the time, prompting Scarborough to fire off numerous tweets defending his presence there. At the time, Scarborough said that he and Brzezinski were at the party to set up an interview with the president-elect.

Trump's comments drew immediate condemnation from members of both political parties, with some calling his jabs at Brzezinski beneath the dignity of his office.

Sen. Lindsey O. Graham (R-S.C.), who has long been critical of Trump, tweeted, “Mr. President, your tweet was beneath the office and represents what is wrong with American politics, not the greatness of America.” And Sen. Ben Sasse (R-Neb.), another Trump critic, tweeted: “Please just stop. This isn't normal and it's beneath the dignity of your office.”

Sen. Lisa Murkowski (R-Alaska) weighed in later in the day, tweeting “Stop it! The Presidential platform should be used for more than bringing people down.” She added: "@POTUS, do you want to be remembered for your tweets or your accomplishments?”

Speaker Paul D. Ryan (R-Wis.), who usually declines to comment on Trump's tweets, said Thursday “obviously I don't see that as an appropriate comment.”

“I think — look, what we're trying to do around here is improve the tone and the civility of the debate, and this obviously doesn't help do that,” he said.

But Trump's aides and allies fiercely defended the president, arguing the “Morning Joe” hosts and their guests frequently criticize Trump and the White House in harsh terms including questioning his mental stability, honesty and fitness for office.

“I don't think that it's a surprise to anybody that he fights fire with fire,” deputy press secretary Sarah Huckabee Sanders told reporters Thursday afternoon. She said voters wanted a fighter when they elected Trump and disputed the idea it was distracting from his agenda on issues like health care.

“They didn't elect somebody to sit back and do nothing,” Sanders said of voters. “They knew what they were getting when they voted for Donald Trump and he won overwhelmingly.”

First lady Melania Trump, who has said she would like to make fighting cyberbullying one of her main focuses, has not publicly reacted to her husband's tweets. Stephanie Grisham, a spokeswoman for the first lady, referred reporters to comments that Melania Trump made on the campaign trail about her husband needing to defend himself, including at an April 2016 rally in Milwaukee, where she said: “When you attack him, he will punch back 10 times harder. No matter who you are, a man or a woman, he treats everyone equal.”

Brzezinski responded on Twitter Thursday morning with a photo of the back of a Cheerios cereal box that reads: “Made for Little Hands.” Brzezinski did not explain what she meant by the tweet, although she seemed to be subtly attacking the president for the size of his hands. Mark Kornblau, the NBCUniversal News Group's senior vice president for communications, tweeted: “Never imagined a day when I would think to myself, ‘it is beneath my dignity to respond to the President of the United States.’ ”

An MSNBC spokesman said in a statement: “It's a sad day for America when the president spends his time bullying, lying and spewing petty personal attacks instead of doing his job.”

Trump has long been defensive about the size of his hands, an issue that seemed to start decades ago when Graydon Carter described Trump as a “short-fingered vulgarian” in Spy magazine. Carter, now the editor of Vanity Fair, said that since then, Trump has regularly mailed him tear sheets from magazines with his hands circled in gold Sharpie to highlight the length of his fingers. On the campaign trail, Sen. Marco Rubio (R-Fla.) brought up the size of Trump's hands, prompting Trump to defend himself during a debate, saying: “And he referred to my hands — if they are small, something else must be small. I guarantee you, there is no problem. I guarantee you.”

Trump and the “Morning Joe” hosts have had a roller-coaster relationship. In the early days of his campaign, Brzezinski and Scarborough would regularly allow the candidate to call into their show and speak at length. After Trump's victory in the New Hampshire primary in February 2016, he called in to the show to say: “You guys have been supporters, and I really appreciate it. And not necessarily supporters, but at least believers. You said there's some potential there.” When Brzezinski and Scarborough announced their engagement in spring, Scarborough told Vanity Fair that the president had offered to officiate their wedding.

Brzezinski and Scarborough have also both been critical of Trump — and over the past several months, Brzezinski has raised questions about the president's mental health. She said on the show in March that Trump is “possibly unfit mentally,” and earlier this month, she said the president is “such a narcissist, it's possible that he is mentally ill in a way.”

During the show Thursday, both hosts raised concerns about the president seeming to sideline Secretary of State Rex Tillerson in favor of allowing his son-in-law, Jared Kushner, to act as a de facto secretary of state. Brzezinski said that Trump's behavior is unlike that of any president before him.

“Let’s say someone came into NBC and took over NBC and started tweeting wildly about people’s appearances, bullying people, talking about people in the competition, lying every day, undermining his managers, throwing them under — the person would be thrown out,” she said. “It’s just not normal behavior. In fact, there would be concern that perhaps the person who runs the company is out of his mind.”

Dan Scavino Jr., who oversees the president's social media, tweeted in the morning before Trump: "#DumbAsARockMika and lover #JealousJoe are lost, confused & saddened since @POTUS stopped returning their calls! Unhinged.”

The president claims he no longer watches the show, but it remains popular among lawmakers and is usually playing in the gyms where members of Congress work out in the mornings. Guests on Thursday morning included Sens. Rand Paul (R-Ky.), Joe Manchin III (D-W.Va.) and Shelley Moore Capito (R-W.Va.).

Sen. Susan Collins (R-Maine) tweeted: “This has to stop — we all have a job — 3 branches of gov't and media. We don't have to get along, but we must show respect and civility.”

House Speaker Paul D. Ryan (R-Wis.) said he doesn't think President Trump's tweets about "Morning Joe" hosts Joe Scarborough and Mika Brzezinski are appropriate, on June 29 at the Capitol. (Reuters)

Some lawmakers said Trump's attack on Brzezinski was sexist, a charge he had to fight during the campaign at points, including when he criticized Megyn Kelly, then of Fox News, after she questioned him during a debate on his past comments about women. Trump later criticized her during an appearance on CNN and described her as having “blood coming out of her eyes, blood coming out of her whatever” during the debate.

“I think it's blatantly sexist,” House Minority Leader Nancy Pelosi (D-Calif.) said of Trump's Thursday tweets. “I don't think there's any question about it.”

Mike DeBonis, Paul Farhi and Abby Phillip contributed to this report.