The bill died in a party line vote in the Assembly's committee on public employees, retirement and social security, Mansoor's office said in a news release.
On another front, Mansoor's office confirmed earlier press reports that he is one of four assembly members seeking to carry a concealed firearm into the State Capitol.
As a former Orange County sheriff's deputy, Mansoor has permission to carry a concealed weapon. However, a law that took effect Jan. 1 requires that any lawmakers who want to pack heat inside the Capitol have to get the OK from the sergeant at arms of both the state assembly and senate.
"He's always carried a concealed weapon," a Mansoor staffer said Wednesday. "To him it's kind of a no-brainer."
There's also no particular reason that he wants to be armed while legislating, the staff member said.
"He believes that any citizen or legislator shouldn't be asked why they want to exercise their 2nd Amendment rights," said the representative.
Mansoor will continue to operate in Sacramento unarmed until the senate's sergeant at arms grants him permission, officials said.