Why Alexandria Ocasio-Cortez nominated Bernie Sanders at the Democratic convention

Alexandria Ocasio-Cortez had one minute in the virtual spotlight on the second night of the Democratic convention, and she used it to second the nomination of Vermont Sen. Bernie Sanders for president.

But, but, but … 

Isn’t this all about party unity, and rallying behind Joe Biden as the nominee? Was Ocasio-Cortez, a representative from New York and ardent Sanders backer, going rogue?

NBC News fueled confusion with a tweet, since deleted, saying, "In one of the shortest speeches of the DNC, Rep. Ocasio-Cortez did not endorse Joe Biden."

NBC followed that up with an article saying Ocasio-Cortez had explained her move and congratulated Biden. But it wasn’t until hours later that the network tweeted a correction, saying the tweet "should have included more detail on the nominating process," and that, in fact, Ocasio-Cortez had endorsed Biden earlier.

Ocasio-Cortez found NBC’s response lacking.

"How are you going to fix the incredible amount of damage and misinformation that you are now responsible for?" she tweeted. "Because a 1:15am tweet to slip under the radar after blowing up a totally false and divisive narrative across networks isn’t it."

More than a few conservatives latched on to the moment and touted it as Ocasio-Cortez breaking ranks.

"Representative Alexandria Ocasio-Cortez threw a curve ball when she used her time to endorse Senator Bernie Sanders," wrote the pro-Trump website Trending Politics.

Actually, no curve ball here.

Candidates who come up short in the presidential primaries but meet a certain delegate threshold typically get a nod for their effort during the convention.

"It is a practice or tradition to put forward the names of all candidates with delegates who still intend to vote for that candidate," said Duke University political scientist John Aldrich.

Northeastern University professor Costas Panagopoulos said this has happened before with second-place finishers: Hillary Clinton in 2008, Jesse Jackson in 1988 and Ted Kennedy in 1980.

Panagopoulos said the move is not a sign of disunity.

"Nominating Sanders was partly symbolic, to recognize his strong showing in the primaries and to shore up support for Biden among his supporters," he said.

Indeed, Sanders had already thrown his weight behind Biden. On the first night of the convention, he told his supporters, "We must come together, defeat Donald Trump and elect Joe Biden and Kamala Harris as our next president and vice president."

Ocasio-Cortez’s formal role was to second the nomination of Sanders. In a tweet, she said it was a technical step.

"I was asked to second the nomination for Sen. Sanders for roll call," she wrote. "I extend my deepest congratulations to Joe Biden - let’s go win in November."

In short, Ocasio-Cortez wasn’t breaking from the script. She was following it.