The organizers behind the upcoming Women’s Convention are being criticized for inviting Sen. Bernie Sanders to speak during the event's opening night.

The Women’s Convention is run by the leaders of January’s Women’s March movement, which saw five million women join protests around the world.

The convention says on its website that “We are the leaders we have been waiting for,” and hopes to bring together activists and political leaders to equip and inspire ahead of the 2018 US midterm elections.

The announcement of Sanders’ speech at the conference with the theme “Reclaiming our Time” was almost immediately followed by widespread criticism on social media and by leading organisations, including EMILY’S List.

“This announcement sends the wrong message to women everywhere,” read a statement from EMILY’S List, which has helped elect pro-choice Democratic women since it was created in 1985.

“We have more women leaders in elected office than ever before … EMILY’s List is proud to have supported many of those women every step of the way, and we know that there is a tidal wave of rising stars coming behind them. The choice of Senator Sanders sends the wrong message,” the statement said.

As of Thursday night, the convention had 39 scheduled speakers listed on its website and only two – Sanders and Abdul El-Sayed, who is running to be the first Muslim governor in the US – appear to not be female.

In response to calls to select a woman to open the convention, Tamika Mallory, the co-president of the Women’s March Board, tweeted that 78-year-old California Rep. Maxine Waters – who is currently serving her 14th term and coined the phrase “Reclaiming our Time” – is actually headlining the conference.

However, a search of the Twitter and Facebook accounts of Women’s March did not find any use of the term ‘headline’ and Rep. Waters’ name. The group’s Twitter account stated that Waters would be “joining” the convention and they also tweeted out a media report that Waters would be “attending.” This language is different to most conferences that usually announce their “headline speakers” by explicit use of that phrase.

As people online began suggesting dozens of alternative opening-night speakers, including women senators, the Women’s Convention released its own statement saying that “We all know how busy women leaders are.”

“We invited many elected officials to our convention that align with the purpose and mission of our existence – to harness the political power of diverse women and their communities to create transformative change.

We are thrilled that Rep Maxine Waters and Senator Sanders will be speaking at the Women’s Convention. We all know how busy women leaders are, and we are grateful for the support of women like Secretary Clinton along with Senators Harris, Warren and Gillibrand. Although their schedules did not allow them to join us in Detroit the weekend of October 27.”