The nation has seen an unusually large number of cycles of late during which only one major party flips U.S. Senate seats

At the onset of the 115th Congress, it appeared that the electoral math spelled doom for the Democratic Party in 2018’s U.S. Senate races, having to defend 25 seats in its caucus – 10 in states carried by Donald Trump in 2016 – compared to just eight for the GOP. [Now, including special elections, the updated numbers are 26 and nine].

Then, as Donald Trump’s approval ratings sunk into the 30s last year, there was chatter of a potential Democratic takeover of the senate, with the party in a strong position to knock off Dean Heller in Nevada and pick up open seats in Arizona and Tennessee.

But with a sustained strong economy and Trump’s marks inching above 40 percent once again, it appears that a handful of Democratic incumbents will remain in tossup races (e.g. Bill Nelson of Florida, Joe Donnelly of Indiana, Claire McCaskill of Missouri, Heidi Heitkamp of North Dakota) while each of those three aforementioned Republican seats remain in play.

In other words, it is certainly a plausible scenario for both parties to pick up seats this November – an electoral outcome that has been particularly unusual during the last decade.

During five of the last six election cycles, only one major party has flipped U.S. Senate seats – something never previously seen with this frequency during the direct election era:

  • 2006: Democrats flipped six seats in Missouri (won by Claire McCaskill), Montana (Jon Tester), Ohio (Sherrod Brown), Pennsylvania (Bob Casey), Rhode Island (Sheldon Whitehouse), and Virginia (Jim Webb)
  • 2008: Democrats picked off eight seats in Alaska (Mark Begich), Colorado (Mark Udall), Minnesota (Al Franken), New Hampshire (Jeanne Shaheen), New Mexico (Tom Udall), North Carolina (Kay Hagan), Oregon (Jeff Merkley), and Virginia (Mark Warner)
  • 2010: Republicans flipped six seats in Arkansas (John Boozman), Illinois (Mark Kirk), Indiana (Dan Coats), North Dakota (John Hoeven), Pennsylvania (Pat Toomey), and Wisconsin (Ron Johnson)
  • 2014: Republicans picked off nine seats in Alaska (Dan Sullivan), Arkansas (Tom Cotton), Colorado (Cory Gardner), Iowa (Joni Ernst), Louisiana (Bill Cassidy), Montana (Steve Daines), North Carolina (Thom Tillis), South Dakota (Mike Rounds), and West Virginia (Shelley Moore Capito)
  • 2016: Democrats flipped two seats in Illinois (Tammy Duckworth) and New Hampshire (Maggie Hassan)

[In 2012, Democrats gained seats in Indiana (Joe Donnelly) and Massachusetts (Elizabeth Warren), Republicans picked off Nebraska (Deb Fischer), and an independent flipped Maine (Angus King). Technically, Democrats also flipped Connecticut with Chris Murphy succeeding independent-Democrat Joe Lieberman].

From 1950 through 2004, it was not common to see such partisan uniformity in senate seat pick-ups. During that 28-cycle span, both parties managed to flip at least one seat in all but six cycles: Democrats in 1958 (+13) and 1990 (+1) and Republicans in 1960 (+2), 1966 (+3), 1980 (+12), and 1994 (+8).

The string of three consecutive cycles with only one major party flipping seats in 2006/2008/2010 is a record never previously matched.

Single party gains in the U.S. Senate had occurred in back-to-back cycles four times previously – 1926 (Democrats)/1928 (Republicans), 1932 (Democrats)/1934 (Democrats), 1946 (Republicans)/1948 (Democrats), and 1958 (Democrats)/1960 (Republicans) – and one time since: (the aforementioned 2014/2016 cycles).

Meanwhile, it has been 20 years since the last time both Democrats and Republicans picked off at least three seats in the chamber during the same cycle – a feat seen eight times from the 1950s through the 1990s: in 1952, 1954, 1956, 1972, 1976, 1978, 1988, and 1998.

In 1998, Democrats knocked incumbents out of office in New York and North Carolina and captured an open seat in Indiana while the GOP picked off an incumbent in Illinois and flipped open seats in Kentucky and Ohio.

As highlighted in the recent election cycles above, when one party seems to have all the momentum (Democrats in 2006, 2008; Republicans in 1994, 2010, 2014), the other party fails to make any inroads in elections to the nation’s upper legislative chamber and loses seats.

That was not always the case.

For example, even when Richard Nixon nearly ran the Electoral College table during his 1972 reelection bid and crushed George McGovern with 60.7 percent of the popular vote at the top of the ticket, the Democrats still managed to flip six U.S. Senate seats in Colorado (Floyd Haskill), Delaware (Joe Biden), Iowa (Dick Clark), Kentucky (Walter Huddleson), Maine (William Hathaway), and South Dakota (James Abourezk). Republicans, meanwhile, picked up just four seats.

Similarly, Democrats picked off four seats in 1956 during Dwight Eisenhower’s decisive win over Adlai Stevenson – all in states won by the popular GOP president: Colorado (John Carroll), Idaho (Frank Church), Ohio (Frank Lausche), and Pennsylvania (Joseph Clark).

And during Ronald Reagan’s rout over Walter Mondale, Democrats flipped three seats – all in states carried by the president: Illinois (Paul Simon), Iowa (Tom Harkin), and Tennessee (Al Gore).

But 2018 is a midterm cycle.

And so, the question is which scenario appears more likely to occur?

1) Only Democrats will flip seats, just like the party not in control of the White House did in 1990, 1994, 2006, 2010, and 2014

2) Republicans will flip more seats despite controlling the White House (e.g. 2002) due to having so few seats to defend

3) Each party will flip a couple of seats (e.g. 1998)

What do you say, November?

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  1. Nikoli Orr on July 2, 2018 at 12:42 am

    1. “Technically, Democrats also flipped Connecticut with C Murphy succeeding ‘independent-Democrat’ J Lieberman”. Said flip occurred at all in 2006 in no small part because the Nutmeg State lacked a so-called Sore Loser’s Law (apparently still the case), and the R nominee proved pathetically weak.
    2. “During five of the last six election CYCLES…” Current US Ambassador to New Zealand Scott Philip Brown stunningly flipped a seat not held by a R since early 1953 (true, the switch happened on a different date from the 6 already noted).
    3. Unlike the contests at other levels, TWO seismic forces are operating cross purposes this cycle, namely the hyper-intensified partisanship (or perhaps more specifically, unconditional fealty toward a certain demagogic cultish figure) and the natural pull away from the party of presidential power (maybe matching the intensity shown last year, adamantly opposing his policies and persona). The Rs seem poised to lose at least AZ (a seemingly sure-fire pickup for the Ds should “Sheriff Joe” become the R nominee); the Ds seem to be at the greatest risk of losing (in descending order) IN, home turf of Pence; MO, Greitens no longer casting a pall; and FL, with the more visible and far more wealthy outgoing governor Rick Scott challenging a state institution, who might well be making his state’s black voters for granted.

    • Dr. Eric Ostermeier on July 2, 2018 at 2:07 pm

      RE #2. Yes, due to the frequently many months in between specials like MA 2012 (8+ months) or OR 1996 (8+ months) and the general election, they are not counted as part of the ‘cycle’ – though a stand-alone special held on Election Day in November obviously would.

  2. John Chessant on July 2, 2018 at 4:35 pm

    I just noticed that, assuming the parties control the White House for exactly two terms at a time, a senator could be elected to four terms in favorable years by starting in the sixth year of the opposing president’s term (for instance, Republicans in 1998 and 2014, and Democrats in 1990 and 2006). For a Republican first elected in 1998 (a Democratic president’s second midterm): his first re-election would be in a Republican president’s re-election (2004), his second re-election would be in a Democratic president’s first midterm (2010), his third re-election would be in a Republican president’s first election (2016). In theory, his fourth re-election would be in a Republican president’s second midterm (2022), so he’d probably lose.

    Of course, there can be many anomalies, such as a president’s weak showing (as in 2000 and 2016), or a president’s party’s strong showing in a midterm (as in 1998 and 2002). But I wonder if the trend towards the parties holding the White House for exactly two terms (since 1992) might partly explain the shift towards one-party Senate gains. If so, would a strong 2020 Democratic candidate help throw off this trend?

  3. Nikoli Orr on November 11, 2018 at 6:42 pm

    “What do you say, (6th) November ?” Turns out, #2 (the Ds had more terrain to defend; they were also a tad overextended after the successive gains in 2012, 2006, and 2000). If Congress member Sinema is able to hold on to her newfound lead, then each party would switch at least two seats (#3; as for MS class 2, DEMs would seem to be out of luck since Chris McDaniel, rather than appointed Senator Hyde-Smith, failed to make the runoff).

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