A second founding board member of a progressive group inspired by U.S. Sen. Bernie Sanders’ failed 2016 presidential run resigned Wednesday, raising concerns of a racial strain within the organization, a report said.

Our Revolution former co-vice chair Catalina Velasquez, an undocumented immigrant and transgender activist, said she left the group because it was insensitive to Latino and immigrant issues. The departure fueled worries of tension between Latinos and African-Americans within the group, Politico reported.

“For the past month, we have been fighting divisive narratives targeting immigrants and pinning us against other oppressed peoples,” Velasquez wrote in a letter she posted on Twitter. “I have faced this with little to no support from the organizational leadership.”

Activists within the group had reportedly complained that issues important to one group, such as immigration reform or Black Lives Matter, have failed to become a focus for the other.

Additional complaints reportedly lodged against the organization included its transparency concerns in making endorsements, a drop-off in fundraising and a failure to influence major elections.

Velasquez’s resignation came a month after the departure of Lucy Flores, the group’s former political director, who left after claiming the group ignored Latino issues, the outlet reported. Insiders have labeled these issues as “growing pains” in the transition from presidential campaign to grass-roots organization.

Our Revolution was formed by Sanders’ top campaign workers after his 2016 presidential primary loss, in a bid to keep his grass-roots army ready for a potential 2020 presidential bid, according to Politico.

Sanders, who was criticized in 2016 for failing to connect with black voters and earn their votes in Southern states, announced Monday that he will seek re-election to the U.S. Senate. The move has been largely viewed as preparation for the 2020 campaign.

While Sanders has attempted to energize support across diverse groups, skeptical parties say he “struggled then and clearly now” reaching black voters.

“The guy’s from Vermont, it’s not like he has a massive [black] constituency,” Ray McKinnon, a black pastor from Charlotte, N.C., told Vox about Sanders, a native of Brooklyn, N.Y. “He failed to connect on a visceral sense.”

Sanders will travel to California in June to meet with trade unionists and rally with Black Lives Matter activists.

Fox News’ Lukas Mikelionis contributed to this report.