2018 Colorado Senate election

The 2018 Colorado State Senate elections took place as part of the biennial United States elections. Colorado voters elected state senators in 17 of the 35 districts in the state senate. State senators serve four-year terms in the Colorado State Senate. The Colorado Reapportionment Commission provides a statewide map of the state Senate here, and individual district maps are available from the U.S. Census here.

A primary election on June 26, 2018, determined which candidates appeared on the November 6 general election ballot. Primary election results can be obtained from the Colorado Secretary of State's website.

Following the 2016 state Senate elections, Republicans maintained effective control of the Senate with 18 members. Democratic state Senator Cheri Jahn switched from Democrat to unaffiliated on December 29, 2017. However, Sen. Jahn decided to still caucus with Democrats. In the 2018 election, Republicans defended 10 seats while Democrats defended 6 seats with Jahn's 1 Independent seat up for grabs.

To claim control of the chamber from Republicans, the Democrats needed to net 1 Senate seat while electing a Democrat to the Independent seat. The Democratic candidate won the Independent seat while Democrats netted 2 additional seats, giving the party majority status in the chamber. The results ultimately led to Democrats gaining a political trifecta for the first time since 2014.

Background
Heading to the 2018 elections, Republicans held a 1-seat majority in the Senate and sought to defend their very narrow majority in the election. Democrats have not held the state Senate since 2014 and aimed at flipping it to potentially achieve a political trifecta as Democrats were expected to retain control of the state House and gubernatorial nominee Jared Polis was considered the frontrunner heading up to the polls.

Five Senate seats were considered vital to determine the political balance of the Senate and even the political outlook of the state. Democratic women dubbed the "Fab Five" were running to defend or win these five competitive districts. Incumbent Republicans Tim Neville and Beth Humenik were seen as the most vulnerable as both narrowly won their races in 2014 and they represented districts in where Democratic presidential nominee Hillary Clinton won in 2016.

Summary of Results
Source:
 * Districts not shown are not up for election until 2020.

Term-limited incumbents
Seven incumbent senators (three Democrats, three Republicans and one independent) are term-limited and unable to seek a third term.


 * Kevin Grantham (R), District 2
 * Kent Lambert (R), District 9
 * Kevin Lundberg (R), District 15
 * Cheri Jahn (I), District 20
 * Andy Kerr (D), District 22
 * Irene Aguilar (D) District 32
 * Lucia Guzman (D), District 34

Retiring incumbents
One incumbent Democrat is not seeking re-election despite being able to do so.
 * Michael Merrifield (D), District 11

Closest races
Seats where the margin of victory was under 10%:


 * 1) District 15, 6.18%
 * 2) District 6, 9.38%

Detailed results
Sources:

Analysis
Democrats handily flipped the state Senate by significantly outperforming their margins compared to 2016 and 2014. Most of the votes that led to the Senate flipping was due to the outsized margins Democratic candidates received throughout the Front Range and ski counties. Independent voters (the largest share of the electorate) along with women voters, younger voters, and suburban voters, helped propel Democrats to victory in many races. Races that were considered competitive but eventually won by the so-called "Fab Five" including Faith Winter, Jessie Danielson, Tammy Story, Kerry Donovan and Brittany Petersen were won by relatively large margins. Due to Democrats flipping the Senate, they were able to gain a political trifecta as Democrats expanded their majorities in the state House and won all statewide races, including for governor.

The results in the Senate and other elections throughout 2018 were called by observers a "blue wave" in which Democrats made historic gains in Colorado.