From Media Release

DENVER, Jan. 30, 2019 -- Today, Colorado Secretary of State Jena Griswold formally withdrew the state of Colorado from Kansas Crosscheck.
Colorado joined Crosscheck in 2008, under Secretary of State Mike Coffman. Since its inception, the program has been riddled with problems including insufficient data and an inability to guarantee the privacy of Coloradans. In addition, the program has been used as a partisan charade, resulting in the potential disenfranchisement of eligible citizens from the voter rolls.
“In the current political climate, where emotion seeks to trump reason, I cannot stand by and let this continue. For that reason Colorado is immediately withdrawing from Crosscheck. I encourage other states and jurisdictions to do the same,” said Secretary Griswold.
Crosscheck was promoted as a data sharing tool for states to maintain their voter registration rolls.  However, the program has faced both lawsuits and extensive criticism for leading to the potential disenfranchisement of eligible voters and exposing voters’ privacy. 
As the letter notes, better list maintenance options exist. Colorado is a founding member of the Electronic Registration Information Center (ERIC). Unlike Crosscheck, ERIC sends states quality list maintenance data on a near continuous basis. Also, unlike Crosscheck, ERIC exceeds industry standards for data security. Twenty-six states and the District of Columbia are members of ERIC.
In the letter, Secretary Griswold urges Crosscheck to close and for other states to join ERIC.