"The worst of the worst is a bad guy actually using a gun, " Walsh said, adding that the 1.5 million gun sales rejected by a failed background check was "a record of success" regardless of how many prosecutions ensued.

CNN: STORY HIGHLIGHTS

The government has rejected calls to abolish GCSEs, but ministers believe they "will over time evolve into a progress check" at the mid-point of the 14 to 19 phase of education.

BBC: GCSEs 'too easy' for brainy pupils

Rubio rejected such a characterization on Tuesday, saying that the framework would require undocumented immigrants to undergo a background check and face immediate deportation if they committed any serious crimes.

CNN: 'Now's the time' to move on immigration, Obama says