Simple logic.
a. criminals dont care about the law...thats why there criminals.
b. the only people this will affect is law abiding gun owners, it will rob the people of the ability to fight back.
c. crime rights are higher in states with stringent gun laws, which are historically LIBERAL.
d. Gun control brings us closer to being a communist police state, another LIBERAL ideal.
i hope this shed some light on the subject.