The GOP’s Long-Term Structural Senate Advantage

Stuart Rothenberg February 20, 2017 · 9:30 AM EST

These days, Republicans have a structural advantage in the fight for the House because of how district lines were drawn earlier in the decade. But the party’s current structural advantage in the Senate may be even more important, since it doesn’t depend on state legislators drawing favorable lines, and the Senate has responsibilities that the House doesn’t.

The GOP’s structural Senate advantage is simply a matter of numbers – the number of states that are reliably Republican or Democratic.

Currently, I would rate 21 states as reliably Republican and 14 states as dependably Democratic in federal races [see list below].  If each party “holds serve” in Senate seats in those states, the GOP begins with 42 Senate seats while Democrats hold only 28 – a substantial difference. (Readers surely will argue over my placement of some states, but disagreements about where Montana, Minnesota or Missouri should be placed does not dilute my point, and in some cases, strengthens it.)

That advantage is particularly noteworthy because the 21 Republican states send 128 representatives to the House of Representatives, while the 14 Democratic states send 156 representatives to the House. In those 35 states, the Democrats represent more people but have fewer Senate seats.

Of course, it has been widely noted that Democrats “waste” voters in the Electoral College by having their voters bunched in relatively few states. The same holds true for the Senate.

To be sure, neither party is guaranteed to win every Senate election in its state. But there is not now a single Democratic state with a Republican senator, and only three Republican states – Montana, West Virginia and North Dakota – currently send Democrats to the Senate, the result of cycle-specific and race-specific factors that surely played a substantial role in those outcomes. 

Exceptions don’t diminish the larger point – that the GOP has a built-in advantage in the fight for the Senate because more states lean Republican than Democratic.

The remaining 15 states (with their 151 congressional districts) are, to varying degrees, competitive, and they constitute the real political playing field in the fight for Senate control every two years.

Not all of those states are equally competitive, of course. Indiana, North Carolina and Missouri are redder than other competitive states, while Maine, Michigan and Minnesota at the very least tilt toward the Democrats. Florida and New Hampshire are among the purest toss-ups.  

Opportunities for each party to gain or lose Senate seats largely depend on which competitive state races are up in a given cycle, and which party controls most of those seats and the White House.

Next year, Democrats (including two Independents who caucus with the party) will be holding 10 of the 11 seats up in competitive races, as well as three seats in reliably Republican states. 

That is a huge burden for the Democratic Senatorial Campaign Committee. The only saving grace for Democrats is that there is a controversial Republican in the White House, which is likely to bring angry voters to the polls rather than contented ones.

Though at first glance the Senate class of 2020 provides great opportunities for the Democrats, that isn’t the case.

While there are 22 GOP seats up for re-election and only 12 Democrats up that year, 18 of those Republicans are in reliably Republican states. Only eight competitive state seats are up in 2020, and they split evenly between the parties, with each holding four seats. Colorado, Iowa, Maine and North Carolina seats are held by Republicans, while Michigan, Minnesota, New Hampshire and Virginia are held by Democrats.

It’s possible, of course, that some reliably Republican seats could be “in play” if the president is extremely unpopular in 2020, but whether or not that happens, the GOP’s structural advantage places an additional burden on Democrats.

The Senate class of 2022, which was just elected last year, includes 14 reliably Republican state seats, nine reliably Democratic seats and 11 competitive state seats. The GOP holds eight of those 11 competitive seats.

None of this means that Republicans have a “lock” on the Senate. Short term factors – a partisan wave, a president’s popularity, the state of the economy, a war, a partisan scandal or even a series of missteps by individual incumbents or nominees – can override the structural dynamic for one party or the other. 

But the Democrats’ structural problems in the Senate can’t be ignored, and the party needs to become competitive in more states to alter the Senate arithmetic.


Republican states (21): Alabama, Alaska, Arizona, Arkansas, Georgia, Idaho, Kansas, Kentucky, Louisiana, Mississippi, Montana, Nebraska, North Dakota, Oklahoma, South Carolina, South Dakota, Tennessee, Texas, Utah, West Virginia and Wyoming.

Democratic states (14): California, Connecticut, Delaware, Hawaii, Illinois, Maryland, Massachusetts, New Jersey, New Mexico, New York, Oregon, Rhode Island, Vermont, Washington.

Competitive states (15): Colorado, Florida, Indiana, Iowa, Maine, Michigan, Minnesota, Missouri, Nevada, New Hampshire, North Carolina, Ohio, Pennsylvania, Virginia, Wisconsin.