Dec. 3, 2021 – Depending on the state, a vacant U.S. Senate seat could be filled via appointment or special election. Here’s why that matters.
Since 2000, 28 U.S. senators have left office before their term ended.
Most (19) did so to hold other offices (e.g., Barack Obama, Joe Biden, and Hillary Clinton to be president, veep, and secretary of state; Jeff Sessions to be attorney general) or due to personal reasons (Al Franken due to a sexual harassment controversy; Thad Cochran due to health reasons). The other eight senators died while in office.
Whether or not the reason was in and of itself a tragedy, each vacancy by a senator had a significant impact on how the Senate operated thereafter.
For instance, when Democratic Sen. Ted Kennedy died in 2009, his passing did more than withdraw an institution in that chamber. It also jeopardized legislative talks over health care reform at the time. His seat would flip to the Republicans in a special election shortly after, and Democrats lost their filibuster-proof majority in the Senate.
Making matters more interesting today, the Senate right now is, in a word, old. The average age of a senator in the current Congress is 64 years old, and there are five octogenarians. And as folks keep pointing out this year, this skew toward old age leaves a bit more to chance when it comes to tragedy and politicking—especially with the current 50-50 split in the Senate between the caucuses and a pandemic that is deadlier for older folks.
So if a senator were to leave office or, heaven forbid, if a senator were to die, how they’re replaced depends on their state. Let’s look at the different ways this process is done and why they matter.
The Two(ish) Ways States Fill Senate Vacancies
Each state has one of two ways to fill a vacancy: they have the governor appoint a replacement to finish the late senator’s term, or they hold a special election to fill the seat.

Naturally, there are some minor but important differences in the ways states appoint or elect new senators. Most states use gubernatorial appointments, but nine states require the replacement to belong to the same political party as the late or vacating senator. In Hawaii and Utah (both states that have that requirement), the governor’s pick must be one of three picks submitted by that political party.


For one comprehensive and searchable list of these states, click here.
Meanwhile, 13 states have special elections within a few months of the vacancy, at most 160 days later. Eight of these have an appointee fill in during the interim, but five don’t (North Dakota, Oklahoma, Oregon, Rhode Island, and Wisconsin).

The Legislative and Political Impact of Senate Vacancies
As mentioned at the top, these vacancies do affect elections and how the Senate works.
In addition to Kennedy’s vacancy, four other seats held by Democrats would be filled through special elections during the 2010 midterms.
When Obama vacated his seat to become president, Illinois Governor Rod Blagojevich selected Roland Burris (D) to serve in the interim; Burris did not seek reelection. Like in Massachusetts, Republicans won this open Senate seat, providing two of the net-six seats they won that year. Following this cycle, the smaller Democratic majority in the Senate faced much stronger headwinds.
Of course, a lot influenced these races—the candidates themselves, the state-level and national political climate, etc. Senate seat vacancies themselves ≠ the seat flipping between parties.
Still, we can guess that they likely played some part in such races, especially when considering more recent elections.
Last year, Arizona Democrat Mark Kelly defeated incumbent Martha McSally, who was appointed to finish the late John McCain’s term after he died in 2018. Meanwhile, Republican Johnny Isakson’s resignation from in Georgia in 2019 eventually led to another flip in the following cycle: appointee Kelly Loefler lost her race to Democrat Raphael Warnock in a runoff.
These vacancies not only had impacts on the races (partially because of who was appointed as the replacement), but also the makeup of the Senate. Both were key to the Republican caucus losing its majority.
The very prospect of Senate vacancies have even impacted non-Senate races. During the campaign to recall California Governor Gavin Newsom, his supporters, his opponents, and political junkies constantly stressed the importance of the recall because whoever won might have to decide who replaces 88-year-old Democratic Senator Dianne Feinstein if she were to leave office for personal health reasons (or die).
Blunt discussions of death aside, it’s difficult to say whether or not this had any real impact on the recall. But it obviously contributed to how Newsom campaigned and how the media explained the race’s importance.
And already, similar thoughts about upcoming races are appearing. As this piece from The New York Times points out, nine senators in the current Democratic caucus are from appointment states with Republican governors; six Republicans are from appointment states with Democratic governors. This “fun” fact could impact how the Senate operates between now and the midterms, and who controls the Senate later.
Critiques of These Processes
I don’t have much to say on which version of these processes is “the best.”
Special elections that quickly follow a vacancy seem like the right choice, since these are more small-d democratic than gubernatorial appointments. However, voter turnout is usually pretty low if it’s a midterm or off-year election, meaning voters are less engaged in picking their new senator anyway.
Obviously, having someone serve at least in an interim capacity when a senator vacates office sounds reasonable—but having that replacement be appointed, especially if there isn’t a special election held within a year of the appointment, is conversely undemocratic. After all, this is why we have the 17th Amendment, which transferred selection of senators from state governments to constituents, in the first place.
Appointments also provide opportunities for corruption. Rod Blagojevich, the Illinois governor who appointed Obama’s replacement in the Senate, actually toyed with the idea of appointing himself before settling on trying to sell the seat for a high-salary job at a nonprofit or foundation and several other things. He was later impeached and removed from office, and sentenced to 14 years in prison before having his sentence commuted by President Donald Trump. Not that this type of thing happens often, but the risk is inherent.
“How do we fill a Senate vacancy?” seems like a simple thing to ask. But the solutions we use influence legislation and elections, and they offer further questions about democracy.
Got thoughts on this piece or ideas for future ones? Feel free to comment below or shoot me a message here.
Other 101PC pieces about elections, appointments, and state governments:
- A Primer on Redistricting
- How State Supreme Courts are Shaped
- Improving Our Elections with Ranked Choice Voting
- 2 Simple Ways to Improve State-level Lobbying
- Policy Grab Bag: 3 Ways to Make Our Democracy More Representative
Related reading:
- Here’s a list of all appointments to the U.S. Senate since the passage of the 17th Amendment in 1913.
- Here’s a list of all senators who have died in office.
- Wikipedia has a good page on senators who have resigned.
- Some folks conducted a study and found that governors typically appoint new senators who reflects the electorate, rather than themself.
- UVA’s Center for Politics used the 2020 election to explain how the topic covered here can influence how a party’s presidential nominee selects their running mate and cabinet members.