The petition titled #PledgeToImpeach, has been pushed by the liberal advocacy group Americans For all of Us Action.
The group’s campaign, By The People, wants to impeach and remove President Trump from office, group spokeswoman Alexandra Flores-Quilty said.
Both members of Congress have been outspoken critics of the president.
“We are really excited and inspired by the leadership of representatives Omar and Tlaib in taking this stand and I hope that other members of Congress join them,” Flores-Quilty said.
The organization tweeted videos of both congresswomen Tlaib and Omar signing the petition.
“I just can’t wait for us to show people, especially the families in my district, that they are being put first and that we’re going to hold everyone accountable to the law, including the president of the United States,” Tlaib said in her video.
When asked if she believes the president should be able to violate the constitution, Omar replied with a decisive “never,” before signing the petition.
By The People is a project of the group Americans For All of Us Action, according to its website. The group is separate from the Americans for All of Us PAC, Flores-Quilty said.
Correction, 5: 15 p.m. | An earlier version of this story misspelled Alexandra Flores-Quilty’s first name.