So much for Democrats coming together in New York’s 14th congressional district.

A feud erupted Thursday on Twitter between Democratic socialist Alexandria Ocasio-Cortez and outgoing Democratic Rep. Joseph Crowley -- the longtime congressman Ocasio-Cortez shockingly defeated in New York’s primaries last month. The victor claimed the incumbent is now mounting a third-party bid.

“.@repjoecrowley stated on live TV that he would absolutely support my candidacy,” Ocasio-Cortez tweeted Thursday. “Instead, he’s stood me up for all 3 scheduled concession calls.”

The 28-year-old progressive Democrat added: “Now, he’s mounting a 3rd party challenge against me and the Democratic Party- and against the will of @NYWFP.”

Crowley, though, responded by saying he isn’t actively challenging her in the general election through the NY Working Families Party, though he will technically be on November’s ballot as a nominee for the party.

He tweeted that he is “honored to have their support” but “I’m not running.” Crowley said it’s not possible for him to be removed from the ballot at this point, short of extreme circumstances.

OCASIO-CORTEZ SCORES VICTORY IN NEW YORK ELECTION SHE DIDN'T RUN IN

“Alexandria, the race is over and Democrats need to come together,” Crowley tweeted. “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.”

Ocasio-Cortez faces Republican Anthony Pappas in November.

Crowley, the chairman of the House Democratic Caucus, was thought by some to be a future speaker of the House before he was defeated in by Ocasio-Cortez last month.

Ocasio-Cortez, a Bernie Sanders supporter who has called for the abolition of U.S. Immigration and Customs Enforcement (ICE), had gained the endorsement of several left-wing groups, including MoveOn and the Democratic Socialists of America (DSA).

Fox News’ Samuel Chamberlain contributed to this report.