Cassie Tanner, a former legislative aide, has accused Lebsock of unbuttoning her blouse at a Young Democrats event in 2015.
Opening day of the 2018 legislative session is marked by a call to high ideals and staking out territory on key issues.
The #MeToo movement has reached a critical juncture at the Colorado Capitol as lawmakers return to Denver Wednesday.
House Speaker Crisanta Duran and Senate President Kevin Grantham will spend the early part of the session addressing their own workplace issues.
Formal complaints have been filed against two Democratic House members and two Republican senators. All have denied the allegations.
In an executive branch with more than 30,000 employees, Colorado's governor found 62 sexual harassment complaints over five years.
Radio reporter Bente Birkeland has uncovered numerous tales of sexual harassment at the state legislature involving senators and representatives, and the people who work beside them.
Former interns say two Republican state senators acted inappropriately toward them. One may file a formal complaint.
"I am being harassed and I am being violated and accusations against me are not true," Lebsock told reporters at the state Capitol.