Colorado Democrats advanced ammunition limits, expanded background checks, and other gun measures during a debate that drew the attention of Vice President Joe Biden, who called four lawmakers.
The Democratic-controlled House gave the initial OK to the bills Friday night after a daylong debate. The preliminary votes set up final actions on the measures Monday.
The Democratic gun-control package that advanced also includes banning concealed weapons on public college campuses, and requiring that gun buyers pay for their background checks.
Biden called three freshman lawmakers in moderate districts to talk about the debate, as well as Democratic House Speaker Mark Ferrandino.
Democratic Gov. John Hickenlooper has said he supports the background checks on all gun sales, and possibly the magazine restrictions.
The Democratic-controlled Senate still needs to consider the bills.