A group of female Democratic senators led the way in calling for Minnesota Democratic Sen. Al Franken to resign Wednesday after seven allegations of sexual harassment, a number that swelled after Sen. Kirsten Gillibrand of New York became the first to call for him to step down.

One by one, Franken's Democratic colleagues said he should step down from Congress in the wake of the accusations. After Gillibrand made her initial statement, nine others — Sens. Mazie Hirono of Hawaii, Claire McCaskill of Missouri, Maggie Hassan of New Hampshire, Patty Murray of Washington, Kamala Harris of California, Tammy Baldwin of Wisconsin, Debbie Stabenow of Michigan, Heidi Heitkamp of North Dakota, and Dianne Feinstein of California — followed suit.

Murray was the first member of Senate Democratic leadership to urge Franken to resign.

An aide to Sen. Elizabeth Warren, D-Mass., said the senator believes Franken should step down and told him so privately. Warren, however, has not issued a formal statement on the Minnesota Democrat's future in the Senate.

Sens. Bob Casey, D-Penn., Sherrod Brown, D-Ohio, Ed Markey, D-Mass., Patrick Leahy, D-Vt., Jeff Merkley, D-Ore., Ron Wyden, D-Ore., and Joe Donnelly, D-Ind., later joined their female colleagues.

“As elected officials, we should be held to the highest standards — not the lowest. The allegations against Sen. Franken describe behavior that cannot be tolerated. While he’s entitled to an Ethics Committee hearing, I believe he should step aside to let someone else serve,” Gillibrand tweeted Wednesday.

Illinois Sen. Dick Durbin, the minority whip for Senate Democrats, also to call on Franken to resign later on in the afternoon.

"Senator Franken’s behavior was wrong. He has admitted to what he did. He should resign from the Senate," he tweeted.

Hirono was the second senator to release a call for Trump to resign.

"Today, I am calling on my colleague Al Franken to step aside. I’ve struggled with this decision because he’s been a good Senator and I consider him a friend. But that cannot excuse his behavior and his mistreatment of women," Hirono tweeted. "TIME Magazine, by naming ‘The Silence Breakers’ as their ‘People of the Year,’ is recognizing what women have always known: there are men among us who use their positions of power and influence to manipulate, harass, and assault women. What is new here is the women. We are, all of us, speaking out, naming names and demanding that the harassers take responsibility for their behavior. I am proud of each of the women who has come forward, and heartened by the changing climate that has received their stories with acceptance and compassion."

"My hope is that this moment for a cultural change will result in women no longer being viewed as objects or toys, but recognized for their abilities and achievements. As regular human beings. Women have endured this behavior, which for too long has been ignored and tolerated," she continued. "But no longer. We can only create a culture where women are respected as equals if we all step forward and be part of the change by holding everyone, especially our leaders, accountable."

“I’m shocked and appalled by Sen. Franken’s behavior. It’s clear to me that this has been a deeply harmful, persistent problem and a clear pattern over a long period of time,” Murray said in a statement. “It’s time for him to step aside.”

“It is clear that Al Franken has engaged in a pattern of egregious and unacceptable behavior toward women. He should resign,” Hassan tweeted. "We are experiencing a change in our culture that is long overdue, and we must continue working to empower all women and do everything we can to prevent sexual harassment, misconduct, and assault."

“Al Franken should resign,” McCaskill tweeted.

“Sexual harassment and misconduct should not be allowed by anyone and should not occur anywhere,” Harris tweeted. “I believe the best thing for Senator Franken to do is step down.”

"I agree with my colleagues who have stepped forward today and called on Senator Franken to resign," Casey said. "We can’t just believe women when it’s convenient."

“Senator Franken’s conduct and behavior are unacceptable and he should resign," Donnelly said in a statement. "I believe there is more work to be done to protect victims of sexual harassment and to reform the system of filing and settling harassment claims in Congress. I support reforms to protect victims, increase transparency and ensure that taxpayers do not have to pay for settlements made by members of Congress.”

"We have a serious problem in this country with sexual harassment and assault – in Congress, in Hollywood, in business, in the military – everywhere. I am grateful to the victims of who have had the bravery to come forward. Their courage has created a movement that is bringing about change," Brown said in a series of tweets. "I have listened to them. I have listened to my female colleagues, to women I work with and women in my life. And I agree the time has come for Senator Franken to step aside."

Heitkamp praised the women who have spoke about Franken's alleged sexual misconduct, calling them "brave," and said she was "concerned and disappointed by the behavior detailed in the allegations."

"We must commit to zero tolerance – which is where I believe we as a country and Congress should be – and that means Senator Franken should step down," she said in a statement.

Colorado Sen. Michael Bennet added his voice to the calls for Franken to resign just before 1 p.m.

"Sexual harassment and misconduct are never acceptable. I understand Senator Franken will make an announcement tomorrow morning, and I'm confident he'll do the right thing and step aside," he said.

Murray's colleague in the Senate from Washington, Sen. Maria Cantwell, also called on Franken to resign.

"Senator Franken’s actions are disturbing, egregious, and demonstrate a pattern of serious misconduct and abuse. It is time for Senator Franken to resign from office," she tweeted.

Sen. Tammy Duckworth, D-Ill., said she was "deeply disappointed by Senator Franken's behavior," and urged him to step aside.

"To all those across America who have come forward to share their stories over the past few months: thank you," Duckworth said in a statement. "Your courage and strength in driving this long-overdue national conversation is awe-inspiring. As national leaders, we must hold ourselves to a higher standard—and we must lead by example to ensure that every person is treated with the dignity and respect they deserve."

Joining Democratic senators in urging Franken to step down was Tom Perez, the chairman of the Democratic National Committee.

"Sen. Al Franken should step down," Perez tweeted. "Everyone must share the responsibility of building a culture of trust and respect for women in every industry and workplace, and that includes our party."

At least seven women have accused Franken of sexual misconduct, including groping and forcibly kissing them, both before and during his time in the Senate.

The Senate Ethics Committee is investigating the allegations against Franken.

As the number of women detailing allegations of sexual misconduct against Franken began to grow, some House Democrats said the Minnesota senator should step down, particularly in the wake of accusations women made about inappropriate behavior from former Rep. John Conyers, D-Mich. But until Wednesday, his colleagues in the Senate had remained silent.

Conyers resigned Tuesday.

Laura Barron-Lopez contributed to this story.