Longtime Delaware Sen. Tom Carper announced Monday that he will not seek reelection to a fifth term in the Senate next year.

"After a good deal of prayer and introspection, and more than a few heart-to-heart conversations, we’ve decided we should run through the tape over the next 20 months and finish the important work that my staff and I have begun on a wide range of fronts, many of them begun in partnership with Democrat and Republican colleagues in the Senate and in the House," Carper, 76, said Monday.

At the "top of the list," he said, was the implementation of President Joe Biden's $1.2 trillion Bipartisan Infrastructure Law.

Carper, a staunch Biden ally and the last Vietnam War veteran to serve in the Senate, is a stalwart of Delaware politics. He became the state's treasurer in 1977 before he was elected to the House of Representatives in 1982. He later went on to serve as Delaware's governor in a "seat swap" with term-limited incumbent Mike Castle, a Republican, before running for Senate in 2000.

All told, following his reelection to the Senate in 2018, Carper has been elected to statewide office in Delaware 14 timtes -- a record, according to his office.

"If I ran for a fifth term in the Senate and won, it would be a record 15 statewide elections," Carper said Monday. 

Carper's announcement is the latest in a string of incumbents announcing they will not seek reelection next year, including California Sen. Dianne Feinstein, Michigan Sen. Debbie Stabenow, Indiana Sen. Mike Braun and neighboring Maryland Sen. Ben Cardin.

With Carper's retirement announced, speculation quickly turned to Rep. Lisa Blunt Rochester, the state's lone member of the House of Representatives, as a possibility to replace him.

". @LisaBRochester that’s the tweet!!! #NuffSaid," wrote Democratic National Committee chairman Jaime Harrison on Twitter shortly after Carper's announcement.

Carper said Monday that he spoke to Blunt Rochester, seemingly offering her his endorsement. She previously interned in Carper's office, and later worked with him when he was the state's governor, serving as Deputy Secretary of Health and Social Services and later the state's Labor Secretary.

"One of the people who could have run, maybe should have run six years ago, is our Congresswoman today, Lisa Blunt Rochester," he said, adding: "She was an intern in our congressional office a million years ago."

"We love Lisa and I spoke with her this morning," Carper said. I said, 'you've been patiently waiting for me to get out of the way, and I'm gonna get out of the way. And I hope you are run, and I hope you will let me support that support you in that mission.' And she said, 'Yes, I will let you support me.'"

In a statement of her own, Rep. Blunt Rochester lauded Carper's decades of service to Delaware and expressed gratitude for having worked with him, without addressing the possibility of running to replace him in the Senate.

"No one put more miles in than Tom Carper," she wrote. "No one worked harder for Delaware than Tom Carper. And I’m thrilled that he’ll now get to spend more time with Martha and his wonderful sons. After all, I know that the titles of husband and father have always meant more to him than Senator."

“To me, this is Tom Carper’s legacy," she added. "That he deeply loved our state of neighbors. That he worked tirelessly every single day to make it a better place. And that in his endeavor, he succeeded.” 

Blunt Rochester's office declined to comment to Spectrum News about speculation that she may run for Senate.

Spectrum News' Cassie Semyon contributed to this report.