Democrats scrambled to contain the fallout on Thursday after sexual assault allegations against Sen. Al FrankenAlan (Al) Stuart FrankenOvernight Finance: Senators near two-year budget deal | Trump would 'love to see a shutdown' over immigration | Dow closes nearly 600 points higher after volatile day | Trade deficit at highest level since 2008 | Pawlenty leaving Wall Street group Pawlenty departing Wall Street group as campaign rumors swirl Bachmann won't run for Franken's Senate seat because she did not hear a 'call from God' MORE (D-Minn.) shook the Capitol.

Senators quickly went into damage control mode after a reporter accused Franken of kissing and groping her without her consent during a USO tour in 2006. She released a photo of the then-comedian’s hands on her breasts while she was apparently asleep.

The allegations turned the tables in the Senate, where Republicans had been facing a daily barrage of questions about Roy Moore, the GOP Senate candidate in Alabama who is facing multiple allegations of sexual misconduct involving teenage girls.

Several Democratic senators distanced themselves from Franken, who had been considered a potential dark horse for the party’s presidential nomination in 2020.

“Sexual harassment and groping are never OK and never funny. … Senator Franken has begun addressing these issues by calling for an ethics investigation and saying he’s going to cooperate,” Sen. Richard Blumenthal (D-Conn.) said while declining to comment further because of the ethics probe.

Senate Minority Whip Dick DurbinRichard (Dick) Joseph DurbinDems confront Kelly after he calls some immigrants 'lazy' McConnell: 'Whoever gets to 60 wins' on immigration Hoyer: DACA deal a long ways off MORE (D-Ill.) said Franken’s behavior was “wrong,” while Sen. Tim KaineTimothy (Tim) Michael KaineKaine hits Trump over shutdown threat: If you don't want to work, take some extra 'executive time' Dem senators tell Trump he doesn’t have ‘legal authority’ to launch preemptive strike on North Korea McConnell must go nuclear: Abolish the legislative filibuster MORE (D-Va.) called it “unacceptable.”

“What I saw was horrible. ... We got to make it clear that this is not humor. This is about power issues, gender issues,” Sen. Ben CardinBenjamin (Ben) Louis CardinMenendez to regain spot as top Foreign Relations Dem US could reinstate security assistance if Pakistan takes 'decisive' steps Cardin files to run for third term MORE (D-Md.) said.

Leeann Tweeden, a radio anchor for Los Angeles’s KABC, wrote on Thursday that Franken crafted a skit involving Tweeden during the trip that included a kissing scene. She said Franken pressured her into practicing the routine and then aggressively kissed her despite her objections.

“I felt disgusted and violated,” she wrote. “I tried to let it go, but I was angry.”

Franken is the latest high-profile figure to face harassment allegations, with current and former female staffers increasingly emboldened to go public with the treatment they’ve received on Capitol Hill.

Four in 10 female staffers who responded to a Roll Call survey earlier this year said they believed Capitol Hill had a sexual harassment problem, while 1 in 6 said they had experienced it personally.

And the Senate, in response to pressure from both parties, passed a resolution late last week that made its anti-sexual harassment training mandatory for senators and staff.

The allegations against Franken initially appeared to catch Democratic senators flat-footed, with several declining to weigh in or noting they had just read stories about the incident as they made their way toward the Senate chamber.

Sen. Tom CarperThomas (Tom) Richard CarperOvernight Regulation: EPA sued over water rule delay | House passes bill to ease ObamaCare calorie rule | Regulators talk bitcoin | Patient groups oppose FDA 'right to try' bill Dem senator questions EPA on stark decline in grant awards Green group backs Sens. Baldwin, Nelson for reelection MORE (D-Del.), who later released a statement condemning Franken’s behavior, noted that he couldn’t talk because he needed to vote and “I don’t like to miss votes.” 

Democratic Sens. Jeanne ShaheenCynthia (Jeanne) Jeanne ShaheenSenators call for probe into US Olympic Committee, USA Gymnastics after abuse scandal Trump officials take heat for declining Russia sanctions Schumer to Trump administration: Who met with Putin's spy chief? MORE (N.H.), Brian SchatzBrian Emanuel SchatzSocial media users slam Ryan for tweet on .50 pay hike Live coverage: Trump delivers his first State of the Union Senate Dems call Trump's reported Census Bureau pick 'deeply unqualified' MORE (Hawaii) and Chrisotpher Coons (Del.) said they couldn't comment because they are members of the Ethics Committee. 

Sen. Elizabeth WarrenElizabeth Ann WarrenGovernment watchdog finds safety gaps in assisted living homes David Crosby: Shared dislike for Trump could reunite Crosby, Stills, Nash and Young Dem senators tell Trump he doesn’t have ‘legal authority’ to launch preemptive strike on North Korea MORE (D-Mass.), who frequently ignores reporters around Capitol Hill, avoided questions, while Sen. Maria CantwellMaria Elaine CantwellGreen group backs Sens. Baldwin, Nelson for reelection The US is falling behind in artificial intelligence research WHIP LIST: Shutdown looms as Senate lacks votes to pass House spending bill MORE (D-Wash.) remained silent as reporters asked her about Franken as well as drilling in the arctic. 

Sen. Joe ManchinJoseph (Joe) ManchinMcConnell: 'Whoever gets to 60 wins' on immigration Manchin: Senators should sign pledge not to campaign against each other  GOP senators turning Trump immigration framework into legislation MORE (D-W.Va.) appeared flabbergasted as he spoke to a swarm of reporters, repeatedly saying that he wanted to speak with Franken.

“I just heard. I just heard, and … I would like to hear from Al,” he said. “I just want to hear from Al. I just want to hear Al’s explanation.”

Franken kept a low profile throughout the day, skipping the Senate’s four votes and a closed-door Democratic caucus lunch.

A spokesman for Franken didn’t respond to a request for comment about his schedule, but sources told CNN that the senator apologized to his staff on Thursday.

The senator initially released a brief statement saying that he didn’t "remember the rehearsal for the skit in the same way, but I send my sincerest apologies to Leeann. ... As to the photo, it was clearly intended to be funny but wasn’t. I shouldn’t have done it.”

But that appeared to frustrate some of his colleagues, who were quick to say they believed Franken’s accuser.

“They are deeply concerning, and I expect to hear more from Sen. Franken,” Gillibrand told reporters during her press conference on military sexual assault.

She added separately that she did not believe Franken’s initial apology was sufficient.

Sen. Tammy DuckworthLadda (Tammy) Tammy DuckworthDuckworth fires back at Trump: I swore an oath to the Constitution, not 'Cadet Bone Spurs' EPA to jumpstart 'war on lead' with strategy meeting Overnight Regulation: Dems go on attack during EPA chief's hearing | Mnuchin promises more Russia sanctions | Regulators subpoena major bitcoin exchange | New lawsuit over FDA e-cig rule MORE (D-Ill.), asked if she thought Franken’s accuser was credible, added, “I tend to believe her.”

“I think that women should be able to feel safe and free in their workplace, and if that there are such allegations they should come forward,” she added, asked if she was worried about additional allegations against Franken.

The Minnesota senator released a longer apology on Thursday afternoon and said he would cooperate with an ethics investigation.

“I respect women. I don't respect men who don't. And the fact that my own actions have given people a good reason to doubt that makes me feel ashamed,” Franken said in his second statement.

But Democrats were quick to get out ahead of Franken, coalescing behind an ethics investigation after Senate Majority Leader Mitch McConnellAddison (Mitch) Mitchell McConnellDems confront Kelly after he calls some immigrants 'lazy' McConnell: 'Whoever gets to 60 wins' on immigration Overnight Defense: Latest on spending fight - House passes stopgap with defense money while Senate nears two-year budget deal | Pentagon planning military parade for Trump | Afghan war will cost B in 2018 MORE (R-Ky.) publicly urged the committee to review the matter.

“I hope and expect that the Ethics Committee will fully investigate this troubling incident, as they should with any credible allegation of sexual harassment,” Senate Minority Leader Charles SchumerCharles (Chuck) Ellis SchumerGOP lawmaker: Dems not standing for Trump is 'un-American' Trump called for unity — he didn’t even last a week Overnight Defense: GOP plays hardball by attaching defense funding to CR | US reportedly drawing down in Iraq | Russia, US meet arms treaty deadline | Why the military wants 6B from Congress MORE (D-N.Y.) said in a tweet.

“Sexual harassment is never acceptable and must not be tolerated,” he added.

But Schumer, like most Democrats on Thursday, did not respond to a question about whether Franken should resign.

“I feel very strongly that Roy Moore should not be a senator, and I feel strongly that if he is elected that the Senate should have its own response to it. I expect to hear more from Sen. Franken on this issue,” Gillibrand said when asked if Franken should resign from the Senate like Moore should withdraw from his race.

Durbin, asked if Franken should resign, said, “No, no, no, no.”

“I think you go through the ordinary due process. And have this thing judged on its merits,” he said.

Asked if an investigation could lead to the committee recommending that the Senate expel Franken, Durbin added, “It could lead to any number of things. It’s not fair to prejudge it or judge what the committee will do.”

Franken isn’t on the ballot in 2018, but the fallout over his sexual assault allegations quickly spilled over into the midterm battle for the Senate, where Democrats face a challenging map. 

Republicans and allied outside groups quickly demanded that Democrats, in particular senators running in red states carried by President Trump, give back any campaign donations from Franken or his PAC.

Claire McCaskillClaire Conner McCaskillGovernment watchdog finds safety gaps in assisted living homes GOP Senate candidate fundraising lags behind Dems in key races McCaskill challenger links human trafficking to 'sexual revolution' of 1960s MORE must denounce her Democrat colleague and return campaign donations she has received from him. … If McCaskill won’t immediately denounce Franken and return his donations, it will be clear she puts partisan politics over basic decency,” said Bob Salera, a spokesman for the National Republican Senatorial Committee (NRSC).

The NRSC released almost identical statements targeting other Democrats up for reelection, including Manchin and Sens. Jon TesterJonathan (Jon) TesterDemocrat Manchin: Pence attacks prove ‘they don't want bipartisanship’ in Trump admin Tester invited the Border Patrol Union’s president to the State of the Union. What does that say to Dreamers?   These Democrats will have a hard time keeping their seats in 2018 MORE (Mont.), Bill NelsonClarence (Bill) William NelsonInterior head to travel to Carolinas to discuss off shore drilling Overnight Finance: Trump touts trade agenda in State of the Union address | Consumer Bureau ruled constitutional | Fed leaves rates unchanged Green group backs Sens. Baldwin, Nelson for reelection MORE (Fla.) and Heidi HeitkampMary (Heidi) Kathryn HeitkampHouse passes bill to ease menu labeling rules under ObamaCare In 2018, Trump must be the small-business champion he claimed to be GOP goes on offense with 20-week abortion vote MORE (N.D.).

Tester, asked if the NRSC was going too far, said, “I’ve been focused on the [Veterans Affairs] bill on choice. I haven’t been focused on this.”

“Have they asked the people who contributed to Roy Moore to ask for their money back?” Tester asked, as he headed into the Democratic caucus lunch.

But by late Thursday afternoon, Democrats were rushing to donate Franken’s campaign cash.

Tester said he would donate $25,000 in donations “to support the important work” of the Montana Coalition Against Domestic and Sexual Violence.

In addition to Tester, Democratic Sens. Sherrod BrownSherrod Campbell BrownTrump accuses Dems of 'treasonous' behavior Former Ohio football star faces conservative rival in GOP primary fight Dems press Trump for 'Buy American' proposals in infrastructure plan MORE (Ohio), Tammy BaldwinTammy Suzanne BaldwinGreen group backs Sens. Baldwin, Nelson for reelection Dems press Trump for 'Buy American' proposals in infrastructure plan Protesters wearing blue fill hearing to protest Grassley ignoring 'blue slip rule' MORE (Wis.), Claire McCaskill (Mo.), Joe DonnellyJoseph (Joe) Simon DonnellyHouse passes bill to ease menu labeling rules under ObamaCare Democrat Manchin: Pence attacks prove ‘they don't want bipartisanship’ in Trump admin Pence optimistic GOP can expand majorities in House, Senate MORE (Ind.), Bob CaseyRobert (Bob) Patrick CaseyDem senator: Pence all 'talk, no action' GOP Senate candidate fundraising lags behind Dems in key races Overnight Health Care: Senate Dems block 20-week abortion ban | Azar sworn in as HHS chief | Dems demand answers on family planning funds | GOP takes sting out of ObamaCare MORE (Pa.), Gillibrand, Heitkamp, Manchin and Nelson each said they were donating their contributions from Franken.

“The allegations against Senator Franken are serious, hurtful and should be investigated. It was the correct decision for Senator Franken to ask for an Ethics Committee investigation,” Manchin said in a statement. “I am also returning his donations.”

Nelson, whom Franken was supposed to headline a fundraiser for this weekend, added that, "as for the events this weekend, Sen. Franken is no longer available." 

Alexander Bolton and Rebecca Kheel contributed