Democratic presidential candidate Sen. Bernie Sanders, I-Vt., speaks at the Fair Immigration Reform Movement presidential candidate forum in Las Vegas in November 2015. (John Locher/AP)

This post has been updated.

Leaders of the Women’s March apologized Saturday for the “hurt and confusion” among women who disagreed with the decision to have Vermont Sen. Bernie Sanders (I) speak on the opening night of its first national convention.

Critics had protested on social media that Sanders not only had run a negative campaign against Hillary Clinton in last year’s Democratic presidential primary, but also that he and his supporters continue to push the Democratic Party away from its base of women and people of color toward the concerns of the white, working class. Many women were simply disappointed that a man was tapped to kickoff a women’s convention, scheduled for Oct. 27-29 in Detroit.

“We are sorry we caused hurt and confusion for so many of you this week,” read the first in a series of tweets by the Women’s March. Another stated: “We acknowledge the announcement about Senator Sanders gave the impression he is occupying a central role at the convention. (He is not.)”

The group’s initial announcement on Thursday brought brought swift and stinging criticism. Feminist activist and author Roxane Gay posted a tweet calling it “absolutely a disgrace.”

Stephanie Schriock, president of Emily’s List, which works to elect Democratic women who support abortion rights, said choosing Sanders to open the convention “sends the wrong message.” She said in a statement that Emily’s List had reached out to the organizers of the Women’s Convention “to offer our help to strengthen the program.”

The original march in January captured the world’s attention when hundreds of thousands of people, most of them women, showed up in Washington the day after President Trump’s inauguration to protest his election and the issues he ran on, including cracking down on undocumented immigrants and repealing the Affordable Care Act. Millions are estimated to have taken part in spinoff marches in cities around the country and the globe. The march has been credited with boosting civic participation by women, and tens of thousands of women have been inspired to run for Congress and for local and state elected offices.

The Women’s Convention, set to take place Oct. 27-29 in Detroit, is the first national gathering since the original event.

Organizers of the convention defended their decision to invite Sanders, who some consider the most influential figure associated with the Democratic Party — even though he is registered as an independent. In a statement, organizers noted that Rep. Maxine Waters (D-Calif.), who is popular with some progressives for her crusade to have Trump impeached, is the headliner for the convention. The statement also said that other women, such as Clinton and senators Kamala D. Harris (D-Calif.) and Elizabeth Warren (D-Mass.) couldn’t fit the convention into their schedules.

“We all know how busy women leaders are,” the statement reads.

Sanders during last year’s campaign described himself as a democratic socialist. As such, he was often criticized for focusing on economic solutions, while downplaying the role of institutional racism and sexism in social inequalities. He became a hero of white progressives, but could not compete with Clinton’s support among people of color and women. Sanders also lost favor with women because some of his progressive male followers were accused of harassing women and people of color on social media. Earlier this year, he drew the ire of feminists and abortion rights supporters for backing a mayoral candidate in Omaha who had co-sponsored antiabortion legislation.

But he also had a following among some women on the left who thought Clinton was not progressive enough, or because of her role in supporting programs in the 1990s that hurt communities of color and women, including tough anti-crime laws and a rollback of welfare benefits.

Tamika D. Mallory, one of the organizers of the Women’s March, defended the decision to invite Sanders to speak at the convention, reminding critics that Waters was the keynote speaker for the event.

But even a self-described Sanders supporter didn’t think he was the right person to kick off the convention.