Incoming Rep. Alexandria Ocasio-Cortez shot back at a fellow Democrat, outgoing Sen. Claire McCaskill, for referring to her as a “shiny object,” saying it is “disappointing.”

“Not sure why fmr Sen. McCaskill keeps going on TV to call me a ‘thing’ and ‘shiny object,’ but it’s pretty disappointing,” Ocasio-Cortez posted on her Twitter page Saturday about the Missouri senator.

The self-described Democratic socialist, who worked as an organizer for Sen. Bernie Sanders’ presidential campaign, also took McCaskill to task for covering up for GOP lawmakers who privately say President Trump isn’t fit for office.

“I’m also not sure why McCaskill is covering for the GOP by saying they ‘secretly think Trump is nuts’. Nobody cares. Trump is melting down our institutions and inciting division between people. At any time GOP could have checked him and choose not to,” she wrote about McCaskill, who lost her bid for a third term in November’s midterm elections. “They’re accomplices.”

Ocasio-Cortez, who knocked off longtime political power broker Rep. Joe Crowley in June’s Democratic primary, said McCaskill abandoned her principles in her Senate run.

“McCaskill promised she’d ‘100% back Trump up’ on his anti-immigrant rhetoric & lost. In MO, almost all progressive ballot issues won,” said Ocasio-Cortez, 29.

McCaskill, in an interview with CNN earlier this month, questioned Ocasio-Cortez’s sudden rise to fame in the Democratic Party.

“I’m a little confused why she’s the thing,” McCaskill told CNN. “But it’s a good example of what I’m talking about, a bright shiny new object, came out of nowhere and surprised people when she beat a very experienced congressman.”

She also trashed Ocasio-Cortez’s progressive stand on issues like immigration and health care.

“But I hope she also realizes that the parts of the country that are rejecting the Democratic Party, like a whole lot of white working-class voters, need to hear about how their work is going to be respected, and the dignity of their jobs, and how we can really stick to issues that we can actually accomplish something on,” McCaskill said.

In the same interview, she said some Republican lawmakers fear airing their true views on Trump because of retaliation from the president’s base of hard-line supporters.

“Now they’ll tell you, if it’s just the two of you, ‘The guy is nuts,'” McCaskill said.