Thomas R. Carper

DOVER — U.S. Sen. Tom Carper, who has held elected office in Delaware continuously for 40 years, has not yet decided whether he will seek a fourth term in the Senate.

A spokeswoman said Monday in an email:

“Sen. Carper is laser-focused on seeing a number of critical priorities across the finish line before the end of this Congress and is also working on his transition into a new role as ranking member of the Senate Environment and Public Works Committee in the next Congress.

“He will make a decision about whether or not he’ll run for re-election in 2018 sometime in the new year.”

A Democrat first elected to the Senate in 2000, Sen. Carper, 69, is the dean of the state’s congressional delegation. He previously served as state treasurer from 1977 to 1983, U.S. representative from 1983 to 1993 and governor from 1993 to 2001.

A September poll from Morning Consult found 66 percent of Delaware respondents approve of the job he is doing, making him the fourth most popular member of the Senate.

Sen. Carper won re-election in 2012 with 66 percent of the vote. He has never lost an election.

Few politicians have had more of an influence on the state, ranging from Sen. Carper’s chief advisers to his policies. Gov.-elect John Carney, Rep.-elect Lisa Blunt Rochester, Chief Justice Leo Strine and Secretary of State Jeff Bullock, among others, have worked for him in the past, and as governor, he oversaw a financial boom, including the opening of the state’s casinos.