NASHVILLE (AP) — Tennessee Gov. Bill Lee on Thursday announced he's calling a special legislative session in late August to allow the GOP-controlled House to replace the state's House speaker, who has promised to resign after a series of scandals.

The move is the latest development in an unprecedented moment in Tennessee's modern political era as lawmakers grapple with how to smoothly — and legally — switch speakers prematurely. House Speaker Glen Casada said he will step aside August 2 following scandals that were first reported earlier this year as the regular legislative session was concluding. The last speaker resignation came in 1931 in the Senate.

"It is in the best interest of our state to select a new speaker of the House, and so I am calling a special session of the General Assembly for August 23 to accomplish that purpose," Lee said in a statement.

Typically the General Assembly meets during what is called a "regular session," or during the first few months of the year. Yet the governor can call state lawmakers back to the Capitol as long as he issues a proclamation and outlines the issues that must be addressed in an estimated amount of time. In this instance, Lee has asked lawmakers to address some Supreme Court rules.

While Tennessee has seen multiple sessions throughout its history, it's still considered a rare political move. August's special session will be the 60th in the state's history.

The special session — anticipated to take just one day — will follow a House GOP caucus meeting where Republican members will nominate a speaker in advance on July 24. Bylaws require the House Republicans to support their caucus' nominee during the formal August 23 vote.

Casada has been dogged by calls to resign since it was revealed he exchanged text messages containing sexually explicit language about women with his former chief of staff several years ago, among other controversies.

In May, House Republicans voted 45-24 declaring members no longer had confidence in Casada's ability to lead. However, it remained unclear whether lawmakers had the ability to remove a speaker. The Tennessee Constitution is silent on that and legal scholars warned that while the Legislature can expel members, it's unknown if they have the power to elect a new speaker before the end of their two-year terms.

Casada volunteering to leave the leadership position helped alleviate several of the key legal questions.

Looming in the background of the anticipation of the special session are talks of possibly using the event to expel Rep. David Byrd, a Republican who has been accused by three women of sexual misconduct decades ago.

Byrd has not outright denied the allegations, but has said he's truly sorry if he hurt or emotionally upset any of his students.

Furthermore, Byrd has spurned calls to step down and was reelected in 2018 with overwhelming support in his legislative district. He repeatedly refused to answers questions about the allegations.

Majority Leader William Lamberth told reporters earlier this week that to expel any member would require filing a complaint with the House Ethics Committee and conduct an investigation before a vote to remove from Byrd could take place.

In Thursday's statement, Lee didn't ask lawmakers to expel Byrd during the special session, but he has previously said the Republican should address the allegations.