Prosecutors charged Racine Mayor Gary Becker with child-sex felonies Thursday and said he had gone to a mall to meet a 14-year-old girl he thought he had met during an online chat.

A state agent had posed as the girl, and the 51-year-old mayor was arrested Tuesday at the mall in suburban Milwaukee. District Attorney Michael Nieskes said during a news conference after a court hearing Thursday that investigators also found records of 1,800 sexually explicit chats on Becker's computer.

The charges include attempted second-degree sexual assault of a child under 16, possession of child pornography, child enticement, use of a computer to facilitate a child sex crime, attempt to expose a child to harmful material and misconduct in office. At least one city official has called on Becker to resign.

Becker, who is married and has two children, waived his preliminary hearing in Racine County Circuit Court on Thursday afternoon. Racine County Circuit Judge Stephen Simanek set his arraignment for Feb. 10.

The investigation by the state Department of Justice's Division of Criminal Investigation started after city workers who helped Becker fix a problem with his personal computer found pornography files on it and alerted Racine police, the complaint said. Police had passed the case on to state investigators to avoid a conflict of interest.

Becker was elected mayor in 2003 and ran unopposed for re-election in 2007. The Democrat had previously served two terms as a city alderman.

A female who answered the phone at Becker's home Thursday declined to comment. Becker's defense attorney could not be reached immediately comment on the charges.

Common Council President David Maack, who has been serving as acting mayor, told The Associated Press on Thursday that Becker should step down.

"I think it would be in the best interest of the city and himself to resign his position," Maack said. "He has some very serious charges he needs to devote his time and energy to, and the city of Racine doesn't need this cloud hanging over its head."

The Common Council can remove Becker from office before he is convicted with votes from 12 of the city's 15 aldermen, city attorney Rob Weber said.

Becker was released from jail Wednesday after a relative posted his $165,000 cash bond. Simanek reduced his bond to $10,000 Thursday.

Racine is Wisconsin's fifth-largest city, with about 80,000 residents. It sits on Lake Michigan about 30 miles south of Milwaukee.