In this June 9, 2016 photo, a customer shops at Liquor Mart in Boulder, Colo. On June 10, Colorado’s governor signed a bill to gradually allow grocery stores to sell full-strength beer, liquor and wine, the biggest change to state liquor laws since the end of Prohibition. (AP Photo/Brennan Linsley)

DENVER |  Colorado Walmart stores won’t be selling liquor after a bill to allow the sales failed by a single vote Monday in the state Senate.

Senators voted 18-17 to defeat a bill adjusting Colorado’s liquor code a year after Colorado made its biggest alcohol change since the end of Prohibition by allowing more grocers to sell full-strength beer.

The debate wasn’t along party lines. Democrats and Republicans were both ardent supporters and opponents of the Walmart change.

Walmart helped negotiate last year’s alcohol bill, but apparently overlooked a provision making it impossible for some big-box retailers such as Walmart and Target to sell liquor.

This year’s measure was advertised as a “clean-up” measure. But it elicited opposition from senators who argued Walmart would drive more independent liquor stores out of business.