2018 United States Senate election in Indiana

The 2018 United States Senate election in Indiana took place on November 6, 2018, along with other elections to the United States Senate and House of Representatives and various state and local elections. Incumbent Democratic Senator Joe Donnelly lost re-election to a second term to Republican Mike Braun by a 6% margin. This was the second consecutive election for this seat where the incumbent was defeated and/or the seat flipped parties.

This was one of ten Democratic-held Senate seats up for election in a state won by Donald Trump in the 2016 presidential election. In 2017, Politico described the race as "possibly the GOP's best opportunity to seize a Senate seat from Democrats" in the 2018 elections. The primary election was held on May 8, 2018. In October 2018, RealClearPolitics rated the race a toss-up between the Democratic and Republican nominees, with the Libertarian receiving a poll average of 6%.

Background
In 2012, Joe Donnelly was elected to the Senate with 50% of the vote to Republican nominee Richard Mourdock's 44%. In the 2016 presidential election, Republican nominee Donald Trump won Indiana with about 56.5% of the vote to Democratic nominee Hillary Clinton's 37.5%.

Nominee

 * Joe Donnelly, incumbent U.S. Senator

Withdrew

 * Martin Del Rio, Iraq War veteran

Nominee

 * Mike Braun, businessman and former state representative

Eliminated in the primary election

 * Luke Messer, U.S. Representative
 * Todd Rokita, U.S. Representative

Declined

 * Jim Banks, U.S. Representative
 * Susan Brooks, U.S. Representative (endorsed Luke Messer)
 * Mike Delph, state senator (endorsed Todd Rokita)
 * Jackie Walorski, U.S. Representative

Withdrawn

 * Terry Henderson, businessman (endorsed Mike Braun)
 * Andy Horning, Libertarian nominee for the U.S. Senate in 2012 and Libertarian nominee for IN-08 in 2014
 * Mark Hurt, attorney and former congressional aide
 * Andrew Takami, director of Purdue Polytechnic New Albany (endorsed Luke Messer)

Results
[[File:Indiana U.S. Senate Republican primary, 2018.svg|thumb|200px|Results by county: {{legend|#e27f90|Braun}}

{{legend|#aa0000|80–90%}}

{{legend|#cc2f4a|60–70%}}

{{legend|#e27f90|50–60%}}

{{legend|#f2b3be|40–50%}}

{{legend|#ffccd0|<40%}} {{legend|#ffb380|Rokita}}

{{legend|#ffccaa|<40%}}

{{legend|#ffb380|40–50%}} {{legend|#73d873|Messer}}

{{legend|#b6ffa8|<40%}}

{{legend|#afe9af|40–50%}}

{{legend|#73d873|50–60%}}

{{legend|#42ca42|60–70%}} ]]

Declared

 * James Johnson Jr.

Candidates

 * Mike Braun, businessman and former state representative (R)
 * Lucy Brenton (L)
 * Joe Donnelly, incumbent (D)
 * James Johnson Jr. (I)

Debates

 * Complete video of debate, October 8, 2018

Polling

 * Graphical summary


 * with Todd Rokita


 * with Luke Messer


 * with generic Republican

Results
On November 6, 2018, Braun won the general election. He swept southern Indiana, the exurbs of Indianapolis, and most other rural areas in the state. Donnelly ran well behind his 2012 vote totals, winning only in Indianapolis, the university centers (Bloomington, Terre Haute, West Lafayette, South Bend), and the suburbs of Chicago in Northwest Indiana.

Counties that flipped from Democratic to Republican

 * Madison (largest city: Anderson)
 * Spencer (largest city: Santa Claus)
 * Starke (largest city: Knox)
 * Vanderburgh (largest city: Evansville)
 * Scott (Largest city: Scottsburg)
 * Blackford (Largest city: Hartford City)
 * Clark (Largest city: Jeffersonville)
 * Crawford (Largest city: Marengo)
 * Floyd (Largest city: New Albany)
 * Jefferson (Largest city: Madison)
 * Fayette (Largest city: Connersville)
 * Henry (Largest city: New Castle)
 * Howard (Largest city: Kokomo)
 * Wayne (Largest city: Richmond)
 * Vermillion (largest city: Clinton)
 * Perry (largest city: Tell City)
 * Sullivan (Largest city: Sullivan)

By congressional district
Braun won 6 of 9 congressional districts, with Donnelly winning the other 3, including one held by a Republican.