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The Race for the Wisconsin Senate

Much political coverage has been given to Wisconsin’s hotly contested races for Governor and US Senator. Another set of consequential races is also underway for 17 of the state’s 33 senate seats. The State Senate is much more competitive than the State Assembly. Currently, the upper chamber is divided between 18 Republicans and 15 Democrats.1

Democrats have reason to be optimistic about their chances in November. They’ve already flipped two improbably Republican-leaning seats in special elections–though they’ll have to defend one of them (SD-1) again in the much higher-turnout general election. The party needs to win two more seats (without losing any) to win control of the chamber.

The graph below shows the status of each senate election, compared with how that district voted in the 2016 Presidential election. Democrats are defending 5 seats, including 3 which Donald Trump won. Republicans are defending 8 seats.

Two close seats, two very different districts

The two closest seats by past presidential vote illustrate the challenges and opportunities facing Democrats this year. They are SD-5 and SD-31, which voted for Trump by 1.0% and 3.7% respectively. Both are currently open seats, and each represents a very different slice of Wisconsin’s political landscape. SD-5 is located in the historically-Republican bastion of Milwaukee’s western suburbs. It is currently represented by Leah Vukmir who is running for US Senate instead of seeking reelection. Despite its Republican credentials, this is one of just a few (mostly suburban) parts of the state which voted more Democratic in 2016 than in 2012.

Senate District 31 is decidely not suburban. A mostly rural district located along the Mississippi River to the north of La Crosse, it has been represented by Democrat and erstwhile gubernatorial candidate Kathleen Vinehout since 2006. This district shifted distinctly toward the GOP during the 2016 election. Democrats will likely need to do well in both kinds of places in order to win control of the senate.

Republican candidates entered September with more money

Money doesn’t win elections by itself, but it certainly helps. From January 1 to August 31, Republican senate candidates outraised Democrats. The 15 Republican candidates combined to raise $1,569,056, with a median of $81,841. The 15 Democrats raised $1,224,845, with a median of $58,960.

No doubt some of this Republican advantage reflects the fact that 6 of their candidates are incumbents with better-established fundraising networks compared to just 4 Democrats. Moreover, nonincumbent candidates are likely to have just spent lots of money winning their primary on August 14. Many incumbents have also saved up considerable war chests over previous years–something the average challenger has not done.

With all of this in mind, the cash-on-hand split between Republicans and Democrats is still notable, if not necessarily surprising. Republican senate candidates entered the month of September with $2,317,806 compared to just $632,454 among Democrats. The median Republican candidate in a contested race had $134,938 in the bank. The median Democrat in a contested race began September with $44,036.

The graph below compares the cash-on-hand split at the beginning of September with the status of each contested race. In general, Democratic candidates in Democratic seats have largely kept pace with Republican challengers–even in strongly Republican areas like District 1. However, they have been heavily outraised in the three Republican senate seats which Trump won by less than 10%.

September numbers, once they are released, may tell a different story. Perhaps major Democratic donors have been waiting until a few weeks after the August primary to begin their donations in earnest. Nonetheless, Wisconsin Senate Democratic hopefuls began the month of September at a significant financial disadvantage.


  1. The State Assembly has 64 Republicans and 35 Democrats.