Some DNC delegates booed during speeches given by people of color. Here’s what was going on.

The Democratic National Convention in Philadelphia had barely gotten started Monday before some delegates, presumably supporters of Bernie Sanders, started repeatedly booing at the mention of Hillary Clinton’s name.

But the disruptions didn’t end there. Delegates also booed vociferously during the official adoption of the Democratic Party platform — which included remarks from several prominent speakers of color, including Rep. Marcia Fudge (D-OH), former Texas state Rep. Leticia Van de Putte, and Rep. Elijah Cummings (D-MD).

Some Sanders supporters and other progressives are upset because the platform committee, under pressure from the Obama administration, voted down a platform plank opposing the Trans-Pacific Partnership (TPP). The disruptions came to a head when delegates started chanting, “No TPP!” over Cummings, who is the chair of the party platform drafting committee.

It’s pretty clear that those who booed and chanted were doing so because they were upset about the platform, and they also booed white speakers like Barney Frank and Democratic Whip Steny Hoyer.

Yet the boos and disruptions of speakers of color also came at awkward times. Cummings, for instance, was giving a speech on his personal background and the importance of diversity in the Democratic Party — but his words on social and racial justice were completely drowned out by the protests.

Fudge pointedly asked for delegates to “respect” her after trying to talk over the boos — even during lines like, “Where we lift each other up and every person from every race, religion, and sexual orientation is respected.”

Some observers thought the optics were painfully bad for Sanders supporters.

To some progressives, the moment was yet another frustrating reminder of the tense dynamics around identity politics and economic populism during the Democratic primary. Some activists feel that while the economic justice issues Sanders and his supporters push are important, there has often been such a laser focus on those issues that it actively excludes other issues like race and gender.

And at the convention Monday night, those concerns seemed to play out quite literally.