Colorado House Democrats approved new ammunition limits and are considering expanded background checks in a debate that has drawn attention from the White House.
The Democratic-led House voted Monday to ban large-capacity magazines, placing a limit of 15 rounds for firearms, and eight for shotguns. The proposals are responses to the mass shootings in Aurora and Connecticut.
Republicans oppose the measures, saying they restrict Second Amendment rights and won't prevent mass shootings.
Vice President Joe Biden called four Democrats Friday during a daylong debate on the measures. Two freshmen legislators in moderate districts were among those he called.
Other proposals expected to get a vote include banning concealed firearms on colleges and requiring that gun purchasers pay for their own background checks.
The Senate still needs to consider the proposals.