The Supreme Court has interpreted the Second Amendment to grant each citizen an unfettered right to own firearms. Neither Congress nor the States can effectively regulate firearms until this amendment is repealed.
Therefore, the President should propose the 28th Amendment to the Constitution of the United States, which shall read:
Section 1: The Second Amendment to the Constitution of the United States is hereby repealed.
Section 2: Congress shall have the power to regulate, permit, or prohibit the manufacture, sale, importation, and possession of firearms.