Colorado’s Democratic-controlled House on Sunday passed a bill that would ban the sale and transfer of semiautomatic firearms, a major step for the legislation after roughly the same bill was swiftly killed by Democrats last year. 

The bill, which passed on a 35-27 vote, is now on its way to the Democratic-led state Senate. If it passes there, it could bring Colorado in line with 10 other states — including California, New York and Illinois — that have prohibitions on semiautomatic guns. 

But even in a state plagued by some of the nation’s worst mass shootings, such legislation faces headwinds.

Colorado’s political history is purple, shifting blue only recently. The bill’s chances of success in the state Senate are lower than they were in the House, where Democrats have a 46-19 majority and a bigger far-left flank. Gov. Jared Polis, also a Democrat, has indicated his wariness over such a ban.