It was revealed that Representative Alexandria Ocasio-Cortez, the influential first-term Democrat from Queens and the Bronx, will give her coveted endorsement to a fellow progressive, Senator Bernie Sanders.

The two will hold a gathering for supporters in Queens on Saturday. It will be the second major campaign event in New York City recently, after Senator Elizabeth Warren’s rally in Washington Square Park last month, where she was endorsed by the Working Families Party.

Here are some reasons Ms. Ocasio-Cortez is endorsing Mr. Sanders:

They are both unabashed socialists: From his call for universal health care coverage to her campaign for a Green New Deal, both Mr. Sanders and Ms. Ocasio-Cortez have eagerly sought to push the Democratic Party further left than nearly any of their colleagues.

Leaders of their generations: Mr. Sanders is 78. Ms. Ocasio-Cortez just turned 30. They both have come to be seen as the progressive voice of their generations.