A PAIR OF DISTRICT ATTORNEYS who have each served for two decades announced Wednesday they will not run for reelection this year, while Suffolk County DA Rachael Rollins said she plans to take her oath of office Monday as the next US attorney for Massachusetts.

District attorneys Jonathan Blodgett of Essex County and Michael O’Keefe of the Cape and Islands each issued statements saying they do not plan to seek a sixth four-year term.

Massachusetts has 11 district attorneys. Rollins’ upcoming resignation and the announcements from O’Keefe and Blodgett mean at least three of those offices will be held by someone new in 2023.

O’Keefe and Blodgett both indicated they plan to serve out their terms. With about a year left in Rollins’ term, Gov. Charlie Baker will need to appoint someone to succeed her.

In a letter to Baker Wednesday, Rollins said she expects to receive her official commission from President Biden by Friday and that she hoped Baker’s appointee will be “fully prepared to assume the role of District Attorney” on Monday.

Rollins said in the letter that when she was elected in 2018, Suffolk County residents “voted for change and a new vision of what public safety could look like.” She said her vision was to  “divert our overwhelming attention away from the non-serious, non-violent crimes” to focus resources on prosecuting and preventing serious, violent offenses.

She told the governor that the new DA he picks “should respect the voters’ wishes” and have the trust and support of communities most affected by crime and criminal prosecution.

“Required skills for this position now include: a trauma-informed, data-driven, and evidence-based approach to prosecution; showing up and engaging with every single neighborhood that makes up Suffolk County, including Chelsea, Revere, and Winthrop; and recognizing that significant disparities still exist in the criminal legal system,” she wrote. “We cannot move backwards. The people of Suffolk County deserve what they voted for.”

Many public officials announce their plans near the start of an election year, often after discussions with relatives and supporters over the holidays. Fields for various races are starting to take shape, and the candidate mix for prosecutorial posts could also be influenced by whether Attorney General Maura Healey decides to run for governor or seek reelection as the state’s top lawyer.

Blodgett, a Peabody Democrat who has run unopposed in every election since he first claimed his seat with 50 percent of the vote in a 2002 primary, said his decision came after “considerable thought and discussion with my family.”

“I am proud of the team I assembled, who work hard every day to seek justice for victims of crime. Their diligence, determination, ethics, and compassion have served the people of this county well and have made my job deeply rewarding,” Blodgett said.

O’Keefe, a Sandwich Republican, last faced an opponent in 2014, when he defeated Democrat Richard Barry with 56 percent of the vote.

“It has been the honor of my professional life to have been elected five times by the voters of the Cape & Islands and to have led an office of professional and dedicated prosecutors,” O’Keefe said, thanking the region’s voters and expressing appreciation for the support staff, victim witness assistants and police agencies he has worked with.

The Cape Cod law enforcement landscape is in for a shakeup after this fall’s elections, with longtime Barnstable County Sheriff Jim Cummings retiring. Rep. Tim Whelan is a candidate for that seat.

Chris Van Buskirk contributed to this story.