"Cory Booker's campaign is in trouble," Miller said. "Cory Booker is looking for areas in which he can distinguish himself, set himself out of the pack. He's having trouble raising money."
Booker, D-N.J., told CNN that there should be a law banning certain weapons and a "reasonable period in which people can turn in these weapons."
The senator said that America wrongly allows "weapons of war" to be present "in streets and communities" like his own home base, Newark, N.J.
"I do think that holding Cory Booker up as an example of the left wing of the party right now is a little bit unfair to this field of 22," Miller said.
Miller said that the Democratic Party and many other Americans "are in favor of sensible gun control restrictions."
Salem Media host Kevin McCullough agreed with Miller, adding that background checks and three-day waiting periods at gun shows are examples of such restrictions that currently exist.
Booker also recently called for a federal licensing requirement for gun owners.
He compared the potential gun license to a driver's license, which is issued after an applicant demonstrates the proficiency to drive a vehicle.
Under the proposal, applications would be submitted at a designated office similar to the process of obtaining a passport, and the FBI would then verify the licensee's request.
"I am sick and tired of hearing thoughts and prayers for the communities that have been shattered by gun violence -- it is time for bold action," Booker said in a statement.
Miller and McCullough cited Rep. Eric Swalwell, D-Calif., as another 2020 presidential hopeful calling for a federal gun buyback program.