Early in the week, the Senate open seat number rose to five, and it’s possible this is the final such number for this election cycle.

Delaware Senator Tom Carper (D) announced that he will conclude his long political career at the end of this Congress. Doing so means he will have served in elective office for 48 consecutive years when the current term ends, which is ten years longer than President Biden’s tenure as a Delaware politician.

Sen. Carper was first elected state Treasurer in 1976 at age 29 and would then go onto defeat two veteran Republican incumbents, Tom Evans in the 1982 US House race and 30-year Senator Bill Roth in the 2000 campaign. In between, Mr. Carper served as Delaware’s Governor for eight years after his initial election in 1992.

During the retirement announcement, the Senator encouraged At-Large US Rep. Lisa Blunt Rochester (D-Wilmington), one of his former congressional staff members and state appointees, to run as his successor. The Congresswoman was first elected to the House in 2016 and has been easily re-elected ever since. She scored a 55.5% win last November and has averaged a 58.3% vote share over her four congressional elections.

Prior to her election to Congress, Ms. Blunt Rochester was the CEO of the Metropolitan Wilmington Urban League. She had also served in state government as Secretary of the Department of Health and Social Services and the Department of Labor as an appointee of both Govs. Carper and Ruth Ann Minner (D). The latter woman succeeded Mr. Carper in the Governor’s office after his Senate election. As mentioned above, Mr. Carper becomes the fifth Senator to forego re-election in 2024 and fourth Democrat. He joins Sens. Dianne Feinstein (D-CA), Mike Braun (R-IN), Ben Cardin (D-MD), and Debbie Stabenow (D-MI) in the group who are voluntarily ending their Washington careers. All are retiring from politics except for Senator Braun who is running for Governor of Indiana.

Though a consistently Democratic state, the party’s victory margin is typically in the high 50s rather than breaking the 60% threshold. Even President Joe Biden could only log 58.7% from his home state against then-President Donald Trump in 2020. Over his seven elections to the Senate, Mr. Biden averaged 59.2% of the vote. In his two elections as Governor, incumbent John Carney (D) averaged 58.5%.

Do these numbers mean that the Republicans will target the open Senate race? Probably not, particularly if Rep. Blunt Rochester runs, which, for her, will basically be a re-election campaign since she already represents a statewide constituency. The open at-large House race, however, with a credible GOP candidate, might be a race that the National Republican Congressional Committee leadership and strategists at least pay some attention.

It remains to be seen if Rep. Blunt Rochester runs for the Senate – it is presumed she will – but another possibility is outgoing Gov. Carney who is ineligible to seek a third term in 2024. Mr. Carney, himself a former Congressman, could launch a primary challenge for the Senate, which could send Rep. Blunt Rochester into the open Governor’s contest. The latter move is not likely, however, since the Congresswoman could have easily hopped into what was known to be an open race long before Sen. Carper’s announcement.

Considering their longevity in office and age, Sens. Feinstein, Cardin, and Carper were all viewed as retirement probabilities. Now that each has announced that he or she will not seek re-election, it appears only two more potential Senate retirement prospects remain. Those are Utah Senator Mitt Romney (R) and West Virginia’s Joe Manchin (D).

Signs are such that Sen. Romney appears to be preparing for another run though it will be through an unconventional strategy since he is not likely to qualify for the ballot through the Utah party convention process. Sen. Manchin says he will decide about re-election toward the end of the year, and there is a possibility he could run for President as the nominee of the No Labels Party. The latter group is attempting to qualify for the ballot in all 50 states.

At this point, however, none of the five known Senate open campaigns are expected to produce a change in party representation.