State Representative Diana DiZoglio, a Methuen Democrat who just days ago issued a rare public rebuke of House Speaker Robert A. DeLeo, said she is launching a bid for the state Senate.

DiZoglio confirmed Wednesday that she will seek the seat held by Kathleen O’Connor Ives, a Newburyport Democrat who said this week she is not running again.

“I have proven I will stand up for my district and for doing what’s right in my current role the last six years,’’ DiZoglio said. “As a state senator, I would automatically be a chairperson of a committee, and my vote would carry much more weight being one out of 40 elected officials, as opposed to being one out of 160.’’

Last week DiZoglio challenged DeLeo on the House’s use of nondisclosure agreements, calling them “silencing tactics’’ to “cover up misdeeds by politicians and others.’’ DiZoglio unsuccessfully pushed lawmakers to adopt stronger language to ban the use of the agreements, even describing her own experience of signing one as an outgoing House aide in 2011.

In a phone interview, ­DiZoglio acknowledged that any upward rise in the House would be limited under DeLeo, especially after publicly bucking leadership on the House floor last week.

She had also voted against lifting term limits on the speakership in 2015, a vote the House made at DeLeo’s behest, and she was one of a handful of Democrats to vote against the controversial pay raise package the Legislature passed in early 2017.

DiZoglio said that she had been weighing a run for months, but that she hadn’t talked directly to O’Connor Ives before announcing her decision. She said she has $70,000 in her campaign account to start the race and has already scheduled a fund-raiser and campaign kickoff for April 5.

The Senate district includes Amesbury, Merrimac, Methuen, Haverhill, Newburyport, Salisbury, and parts of North Andover. O’Connor Ives, who first won election in 2012, said it was time for a “new chapter’’ in deciding not to seek reelection and pointed to devoting more attention to her family.

“The way I’ve set out to do this is to be as accessible and responsive as possible, participating in meetings, events, and other activities outside of business hours and on weekends in all seven communities I represent,’’ she said in a statement released before dawn. “And now, at the conclusion of this term, that time will be spoken for by a lovely and demanding toddler.

“So, in many ways, I’m disappointed to leave the Senate,’’ she added, “but in my heart I know it’s the right thing to do.’’

O’Connor Ives is the sixth Senator in less than a year to either leave or opt not to seek re-election to the 40-member body. She follows Linda ­Dorcena Forry, the Senate’s only black member, who left for the private sector this year, and Thomas McGee, a former chairman of the state Democratic party, who now is the mayor of Lynn.

Before them, Jennifer Flanagan resigned to join the state’s newly formed Cannabis Control Commission, and James ­Timilty left last spring to take a job as the Norfolk County treasurer. Senator Barbara L’Italien is running for Congress, effectively giving up her chance to seek reelection to her Senate seat.

They may have more company. Senator Eileen M. ­Donoghue is a finalist for the Lowell city manager’s job and is a favorite to replace the outgoing Kevin Murphy, who is retiring April 1. The Lowell City Council is expected to name its selection before the end of the month.

The changes promise to bring a slew of new faces to the Senate, where, on Wednesday, Senator Karen E. Spilka, an Ashland Democrat, confirmed she had secured support to be its leader next year.

Former Senate president Stanley C. Rosenberg stepped down from the post late last year after the Globe reported that four men accused his husband, Bryon Hefner, of sexually assaulting or harassing them while boasting of his influence over Senate business.

The Senate has since launched an Ethics Committee investigation into their former leader. Rosenberg remains in the Senate and has maintained that Hefner had no influence over the chamber’s business.

Current Senate President Harriette L. Chandler has said she does not intend to run for reelection to the position this January.

Reach Matt Stout at matt.stout@globe.com. Follow him on twitter @mattpstout.