Meanwhile, legislative clerks under pressure to release details of sexual harassment complaints released some information, saying the Senate and Assembly had received two complaints each over the past decade. One of the complainants eventually won a $75,000 settlement.
The developments came as both Democratic and Republican leaders of the Legislature defend not releasing details, saying that would intimidate victims from coming forward. Calls for Zepnick's resignation came after two women told the Capital Times newspaper he had kissed them without consent. The women requested anonymity and said they had not filed complaints.
Zepnick has refused to step down. Emily Pritzkow, a spokeswoman for Assembly Minority Leader Gordon Hintz, said Hintz's office was researching possible discipline for Zepnick.
Hintz could remove Zepnick from the committees he serves on and lock him out of party caucus meetings. He could push the Assembly to censure Zepnick, which would equate to a reprimand.
He also could introduce a resolution calling for Zepnick's expulsion, which would involve public hearings in which Zepnick could defend himself and his accusers could speak. It would ultimately take a two-thirds vote by the Assembly to remove him.
Hintz also could try to remove Zepnick through impeachment. The Assembly majority vote would be needed to trigger a trial before the Senate. If two-thirds of the Senate vote to convict, Zepnick would be expelled.
Zepnick didn't immediately reply to an email Monday seeking comment.
The Legislature last considered expelling a member in 2014, when Assembly Republicans discussed throwing out then-Rep. Bill Kramer after he was charged with sexually assaulting a political aide three years earlier. The Republicans scrapped the idea after Kramer announced he wouldn't seek re-election.
The Capital Times newspaper reported Friday that two women who requested anonymity accused Zepnick of trying to kiss them. One woman told the newspaper she was working at the state Democratic convention in 2015 when a drunken Zepnick kissed her. The newspaper described the other woman as a former legislative staffer. She said a drunken Zepnick kissed her during a 2011 party for a state Senate recall candidate.
Zepnick said in a statement he didn't remember the incidents but he apologized to both women. He said he is a recovering alcoholic and made many mistakes during years of "irresponsible drinking."
The newspaper report prompted Hintz to tweet Friday that Zepnick should resign. Senate Minority Leader Jen Shilling called for Zepnick to step down Monday.
Republican Assembly Speaker Robin Vos and other GOP Assembly leaders have criticized Zepnick's behavior but stopped short of calling for his resignation.
Zepnick has represented a swath of Milwaukee since 2002. He was arrested for drunken driving in 2015, pleaded guilty and paid a forfeiture. He also had his license suspended for six months and was ordered to use an ignition interlock device for a year.
The Associated Press filed an open records request with the Senate and Assembly chief clerks' offices for sexual harassment complaints against legislators and employees since 2007. The clerks denied the request last week, citing the victims and the privacy concerns of the accused.
On Monday, Assembly Chief Clerk Patrick Fuller said his office has received two complaints since 2007, one in 2014 and one in 2017. He didn't offer further details.
Senate Chief Clerk Jeff Renk said Monday that his office also has received two complaints over the last decade, one in 2009 and one in 2011. He, too, didn't offer any details.
He did say, however, that one of the complainants also filed a complaint with the state Equal Rights Division alleging she was wrongfully terminated from her job as a legislative aide to now-former Sen. Spencer Coggs. Renk said the ERD complaint contained "sexual harassment language."
It's not clear who allegedly harassed the former aide. Coggs said in an email to the media on Monday that he has never harassed or discriminated against the former aide or anyone else who worked for him.
The Legislature settled the complaint for $75,000 in 2015.