“ In this proceeding, an Alabama circuit court entered an order directing petitioner to certify to the Secretary of State of Alabama the name of respondent as a candidate for nomination for Presidential and Vice-Presidential elector in the primary election of the Democratic Party to be held on May 6, 1952. The Alabama Supreme Court affirmed on the single ground that the order was compelled by Article II, Section 1 and the Twelfth Amendment of the United States Constitution. ”