Sönam wrote:But concerning Obama ... could he interfere? could he say, no it won't happen!, easy or not easy. If it was not for electoralist reasons, could he says no, as far as I am President no one will die from the death penalty? If he was a real great President, could he choose to act so?
No, he can't do that. The death penalty was suspended in by the supreme court of the united states in 1972, and reauthorized by the supreme court in 1976.
It is a state by state issue and it is legal to execute prisoners for capital crimes outlined by the 1976 decision.
The President of the United States has no authority to end the death penalty unilaterally, even if he wanted to.