In an explosive tweet on Thursday, democratic socialist Alexandria Ocasio-Cortez accused Rep. Joe Crowley (D-N.Y.)—who was defeated in a landslide in last month's Democratic primary—of backtracking on his repeated vows to support her in the general election and attempting to sabotage her campaign with a "third party challenge."

"Rep. Joe Crowley stated on live TV that he would absolutely support my candidacy," Ocasio-Cortez wrote. "Instead, he’s stood me up for all three scheduled concession calls. Now, he's mounting a 3rd party challenge against me and the Democratic Party."

"So much for 'Born to Run,'" Ocasio-Cortez added, referring to Crowley's performance of the Bruce Springsteen classic after he conceded last month's primary.

.@repjoecrowley stated on live TV that he would absolutely support my candidacy. Instead, he’s stood me up for all 3 scheduled concession calls. Now, he’s mounting a 3rd party challenge against me and the Democratic Party- and against the will of @NYWFP.https://t.co/Xvb6Jk8N8q — Alexandria Ocasio-Cortez (@Ocasio2018) July 12, 2018

Crowley was quick to deny Ocasio-Cortez's claim that he's running on a third party line and blamed her team for failing to follow through with attempted phone calls.

Alexandria, the race is over and Democrats need to come together. I’ve made my support for you clear and the fact that I’m not running. We’ve scheduled phone calls and your team has not followed through. I’d like to connect but I’m not willing to air grievances on Twitter. https://t.co/hxEeWEpI2O SCROLL TO CONTINUE WITH CONTENT Never Miss a Beat. Get our best delivered to your inbox.





— Joe Crowley (@JoeCrowleyNY) July 12, 2018

As evidence for her claim that Crowley is mounting a third party bid, Ocasio-Cortez pointed to a New York Times report that Crowley refused to vacate the New York Working Families Party line, which he secured after receiving the party's endorsement.

As The Week explains, "New York has a quirky third-party system, which can allow unsuccessful major party candidates like Crowley to be the nominee for a smaller party and therefore still appear on the general election ballot."

In a series of tweets on Thursday, Crowley insisted that he's "not running" and maintained that a candidate can only be removed from the ballot under special circumstances: