KUSA — In all five of the Senate districts that are the most in play on election night, active unaffiliated voters outnumber voters from all political parties, including Democrats and Republicans, according to Colorado Politics.

Voter Guide 2018: Everything you need to know about the upcoming Colorado election

The following five races are up in the air and could go either way come Tuesday, deciding who controls Colorado's upper chamber:

-

District 5 (currently Democrat) - Chaffee, Delta, Eagle, Gunnison, Hinsdale, Lake and Pitkin counties.

This seat is currently held by Democratic Sen. Kerry Donovan of Vail. She won the seat in 2014 in a Republican wave year that saw the Senate flip from Democratic to Republican control. Republicans have held the Senate ever since.

Donovan is up against Olen Lund of Paonia. Lund served on the Delta County Commission from 2004 through 2012.

In June, Donovan garnered 13,707 votes to Lund’s 9,796.

-

District 16 (currently Republican) - Boulder, Denver, Gilpin, Jefferson counties

This seat is currently held by Republican Tim Neville, who is running against Democrat Tammy Story.

Story was a 2016 Democratic candidate for District 25 of the Colorado House of Representatives. She lost to Republican incumbent Tim Leonard.

Four years ago, active Republican voters outnumbered Democrats by 4,000 in Senate District 16, Neville’s seat. That margin, as of September, has evaporated, according to Colorado Politics.

In the June primary, Democrat Tammy Story drew 18,424 votes; Neville won 12,996 votes.

-

District 20 (currently Independent) - Lakewood, Arvada, Ken Caryl, Dakota Ridge, Wheat Ridge

This district is currently held by the Colorado Senate’s lone unaffiliated member, Sen. Cheri Jahn. She's termed out.

Democrat Jessie Danielson from Wheat Ridge represents State House District 24 in the Colorado House of Representatives. She's the Democratic Speaker Pro Tem.

Her opponent, Republican Christine Jensen also of Wheat Ridge, ran unopposed in the GOP primary.

Danielson drew more voters in the June primary, 19,778 to Jensen’s 13,821.

-

District 22 (currently Democrat) - Lakewood, Littleton, Ken Caryl, Dakota Ridge, Edgewater.

Democrat Brittany Pettersen is currently a member of the Colorado House of Representatives (District 28 in Lakewood) but is running against Republican Tony Sanchez for the District 22 seat.

Sanchez was a 2014 Republican candidate for District 22 of the Colorado State Senate, but he was defeated by the seat's current incumbent, Democratic Senator Andrew Kerr.

Kerr is unable to run for re-election in 2018 because of term limits.

Pettersen won 16,066 votes in June; Sanchez took in 11,440 votes.

-

District 24 (currently Republican) - Westminster, Thornton, Northglenn in Adams County

This seat is currently held by Republican Sen. Beth Martinez Humenik of Thornton. She was elected to the Colorado State Senate in 2014.

Her challenger - Democratic Rep. Faith Winter of Westminster - currently represents Colorado House District 35. Winter was first elected in 2014.

In 2014, Democrats held an advantage over Republicans in registered voters by 2,200. That gap is now nearly 5,000.

Winter performed better in the June primary, with 14,313 votes to Humenik’s 9,401.

Read more, including what Colorado House races are the ones to watch, at Colorado Politics.