WASHINGTON — The tension between supporters of Bernie Sanders and Hillary Clinton resurfaced on Tuesday after the Vermont senator announced his second run for the White House.

Longtime Clinton aide Philippe Reines tweeted that the media had given Sanders a "WELCOME BACK!" reception despite his 2016 primary loss while telling Clinton to "go away."

Jess McIntosh, a communications adviser to Clinton's 2016 campaign, focused on Sanders' contention on Vermont Public Radio that "we have got to look at candidates, you know, not by the color of their skin, not by their sexual orientation or their gender and not by their age."

McIntosh shot back on Twitter: "If Bernie is going to start this contest telling us he's at a disadvantage as a white man it is going to be a LONG year."

Sanders is running against four women this time around — Kamala Harris, Elizabeth Warren, Kirsten Gillibrand and Amy Klobuchar — as well as three candidates of color in Harris, Cory Booker and Julian Castro.

A representative for Clinton didn't immediately comment on Sanders' candidacy.

An enthusiastic progressive who embraces proposals ranging from Medicare for All to free college tuition, Sanders stunned the Democratic establishment in 2016 with his spirited challenge to Clinton. While she ultimately became the party's nominee, his campaign helped lay the groundwork for the leftward lurch that has dominated Democratic politics during the Trump administration.

The question now for Sanders is whether he can stand out in a crowded field of Democratic presidential candidates who embrace many of his policy ideas but are newer to the national stage.