Mayor Bill de Blasio criticized a federal proposal to allow licensed gun owners to carry concealed firearms across state lines.
North Carolina Rep. Richard Hudson wrote the bill, saying a gun license should be treated the same as a driver's license.
The NYPD previously said it doesn't support the proposal, and the mayor says he thinks it will put New Yorkers in danger.
"All over the country, we have seen these horrible massacres where people got their hands on, not just weapons, very high-grade weapons, including people who had mental health problems," de Blasio said. "If those kinds of proposals pass, you're going to have a less safe country. It's as clear as that."
Hudson's bill has 158 co-sponsors, including two Democrats.