Alexandria Ocasio-Cortez and Rep. Joseph Crowley, the 10-term incumbent she defeated in a Democratic congressional primary in New York, publicly sparred Thursday over whether Crowley had been sincere in his pledges to support her candidacy in November.

Ocasio-Cortez, the 28-year-old self-described democratic socialist who stunned the political establishment with her upset over Crowley last month, fired off a morning tweet in which she questioned his televised promise on primary night to rally behind her.

Crowley certainly seemed sincere at the time. At his election night watch party, he picked up a guitar and dedicated a version of Bruce Springsteen’s “Born to Run” to Ocasio-Cortez.

But Thursday, Ocasio-Cortez wrote on Twitter that Crowley had “stood me up” on three scheduled concession calls and was now mounting a third-party challenge to keep his 14th Congressional District seat.

The latter charge stems from a quirk in New York election law that allows a candidate to compete for more than one party nomination. While Crowley lost to Ocasio-Cortez in the Democratic primary, he prevailed the same night as the nominee of the New York Working Families Party — which makes him eligible to compete in November.

Earlier this week, the New York Times reported that Crowley’s name would remain on the ballot as the Working Families Party nominee, despite a request by the executive director of the party to have it removed.

In response to Ocasio-Cortez on Thursday, Crowley sought to quell the controversy.

“Alexandria, the race is over and Democrats need to come together,” he wrote on Twitter. “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.”

In subsequent tweets, Crowley acknowledged that there were “lots of questions about the WFP line.”

“Was honored to have their support,” he wrote. “I’m not running. For record you can only be removed from the ballot if 1) you move out of NY; 2) die; 3) be convicted of a crime; 4) accept a nomination for another office (in a place I don’t live).”

Crowley then said he does not meet any of those criteria.

“I don’t plan on moving out of New York, have a clean record, hope God’s will is that I don’t die, and won’t commit what I honestly believe to be election fraud.”

Ocasio-Cortez, meanwhile, made a fresh fundraising appeal over Twitter, writing: “So much for ‘Born to Run.’ If you want to see me in Congress, we need your help now more than ever.”

Later Thursday, Bill Lipton, the director of the New York Working Families Party, suggested a way to resolve the predicament.

“The only remaining way for Crowley to do the right thing is to switch his residency to Virginia, where his family resides and his children already go to school,” Lipton said. “It would fix the problem he created in an instant.”

Lipton said doing so would allow his party to put Ocasio-Cortez on the ballot as their nominee as well as that of the Democrats.