In 2018, Gardner was ranked 4th most liberal compared to ALL Senate Sophomores by GovTrack (that include Democrats in that ranking)
Of the 157 bills Gardner cosponsored in 2017, 41% were introduced by legislators that were not Republican
Of the 53 bills Gardner cosponsored in 2018, 66% were introduced by legislators that were not Republican
https://www.govtrack.us/congress/members/cory_gardner/412406/report-card/2017
https://www.govtrack.us/congress/members/cory_gardner/412406/report-card/2018