STATE HOUSE — An eight-way race for a district that last elected a new representative in the 1970s. A former lawmaker looking to oust an incumbent and make his return after serving federal time for voter fraud. The Republican treasurer candidate's husband vying to take her place in the House.

Those are just three of the contests that will be on the ballot this fall as all 200 seats in the state Legislature come up for election.

More than 100 lawmakers -- 22 members of the 40-seat Senate and 83 in the 160-seat House of Representatives -- are on track to cruise another term without facing an official challenge, according to data from Secretary of State William Galvin's office.

But the new class of legislators seated in January will also include at least 24 new faces, with 20 representatives and four senators either leaving Beacon Hill during this session or opting against re-election bids. There's an opportunity for more newcomers to join by pursuing the steeper climb of challenging an incumbent, an effort being undertaken in 14 Senate districts and 57 House districts.

Even if all incumbents are re-elected, the nine current vacancies and 15 lawmakers not seeking new terms guarantee that 2019 will feature more legislative turnover than 2017, when 12 new representatives and three new senators joined the body.

On the Senate side, the busiest races are for the two currently open seats, last held by Stanley Rosenberg and Lowell city manager Eileen Donoghue

Five Democrats, including two Lowell city councilors, and one Republican are in the mix for Donoghue's seat. Northampton Democrat Chelsea Kline is the only candidate on the ballot for Rosenberg's seat, though at least four others have launched write-in campaigns.

Rep. Diana DiZoglio, a Methuen Democrat, is one of two candidates running for the seat Sen. Kathleen O'Connor Ives will leave at the end of her term. Former Sen. Barry Finegold of Andover is among a field of four as he vies to reclaim the seat he gave up to run for treasurer in 2014, now held by Congressional hopeful Sen. Barbara L'Italien.

Three other former lawmakers are seeking to return to the House.

The race for the Lawrence seat now held by Rep. Juana Matias -- who is running, like L'Italien, in the 10-way Democratic primary to succeed U.S. Rep. Niki Tsongas -- will be a rematch between Lawrence Democrats Marcos Devers and William Lantigua, who have both previously held the seat. Devers was unseated by Matias in 2016, and Lantigua resigned in 2010 after facing criticism for his plan to serve as both representative and mayor.

In Everett, one of the two Democrats who have emerged to challenge Rep. Joseph McGonagle is Stephen "Stat" Smith, newly eligible to run again after a five-year period in which he agreed not to seek office as part of a voter fraud sentence.

Smith, who was elected to the House in 2006, pleaded guilty in 2013 to charges connected to obtaining absentee ballots for ineligible voters and in some cases casting ballots for voters without them knowing it.

McGonagle is one of 15 House Democrats facing primary challenges. Three Senate Democrats -- Adam Hinds of Pittsfield, James Welch of West Springfield, and Jason Lewis of Winchester -- have primary opponents, and Lewis also faces a Republican challenge.

Barnstable Rep. Randy Hunt, who also faces a general election opponent, is the only Republican in either branch with a primary challenger. Three House Democrats also face both primary and general election challengers, Reps. Colleen Garry of Dracut, Jerald Parisella of Beverly and Jim Hawkins of Attleboro.

Reps. Susannah Whipps of Athol and Solomon Goldstein-Rose of Amherst, both of whom left their parties this session to become unenrolled, each have Democrat challengers.

Goldstein-Rose, who was elected as a Democrat in 2016 after longtime Rep. Ellen Story retired, will square off against the winner of a primary between Mindy Domb, whom Story has endorsed, and Eric Nakajima, who finished second in the six-way 2016 primary.

House Democrats facing competition from within their own party include a handful who chair committees or hold other leadership positions: House Ways and Means Chair Jeffrey Sanchez and Assistant Vice Chair Liz Malia, both of Jamaica Plain; Assistant Majority Leader Byron Rushing of Boston; Public Health Committee Chair Kate Hogan of Stow; and Mental Health, Substance Use and Recovery Committee Chair Denise Garlick of Needham.

Four Democrats are bidding to unseat the House's longest serving member, Readville Democrat Rep. Angelo Scaccia, who is running for a 23rd term.

There are seven vacancies in the House, including the seats last held by Sens. Brendan Crighton and Nick Collins, Kingston town administrator Tom Calter, U.S. Sen. Ed Markey aide Jim Cantwell, and three lawmakers who died in office: Reps. Peter Kocot, Jim Miceli and Chris Walsh.

Walsh died May 2, a day after the filing deadline for legislative races. The Framingham Democratic Committee on May 20 decided against caucusing to nominate a candidate for Walsh's seat, leaving no names on the ballot and creating an opportunity for write-in campaigns.

The April death of Miceli, who had represented Tewksbury and Wilmington since 1977, set off a scramble to succeed him. Five Democrats, two Republicans and one unenrolled candidate, are now competing for his seat.

Eight candidates, all Democrats, are also in the mix for the seat now held by Worthington Rep. Stephen Kulik.

Kulik and Reps. Frank Smizik, Cory Atkins, Jay Kaufman, James Dwyer and John Scibak are all retiring after this term.

Seven other representatives, including Matias and DiZoglio, are leaving the House to run for other seats: Keiko Orrall (treasurer), Geoff Diehl (U.S. Senate), Kevin Kuros (Worcester register of deeds), Kate Campanale (Worcester register of deeds), and Evandro Carvalho (Suffolk district attorney).

The residents of Orrall's 12th Bristol District -- Bristol, Lakeville and parts of Taunton and Middleborough -- could still end up with a Rep. Orrall next year. Her husband, Lakeville Republican Norman Orrall, is one of two candidates seeking the seat.

Spouses have succeeded each other in the Legislature before. North Attleborough Republican Rep. Elizabeth Poirier won her seat in a 1999 special election after her husband, Kevin Poirier, resigned from the House.