The drive for a tough federal gun control law has hit a political roadblock. But that's not silencing Joe Biden and Mike Bloomberg.

The loquacious vice president and the outspoken New York mayor on Thursday touted the "importance of passing common sense legislation to reduce gun violence," including the need for a stiff background check system for all gun sales.

They joined families of those killed last December in the shooting massacre in Newtown, Connecticut, to push for new rules. They spoke at New York City Hall as prospects for a ban on semi-automatic weapons styled after military assault weapons appeared to founder.