According to this article, U.S. Senator Rand Paul, whose term expires in 2016, will try to change a Kentucky law that says a candidate cannot appear on the ballot as a candidate for more than one office.
The article says that some of Paul’s allies believe that the Kentucky law is unconstitutional, and they base this on the 1995 U.S. Supreme Court decision U.S. Term Limits v Thornton, which struck down state laws that imposed term limits in congressional elections. However, courts have generally upheld “resign to run” laws, even when the plaintiff who challenged such laws wanted to run for federal office. Courts have ruled that if someone is unwilling to give up his or her old office in the middle of the term, in order to run for Congress, Article One is irrelevant. They say that it is the candidate’s own decision whether or not to run for Congress (and sacrifice the elected position already held). The state law is not prohibiting someone from running for Congress.
By analogy, then, if Paul challenged Kentucky’s law against running for two offices simultaneously, the courts would probably say that he is free to run for re-election to the Senate, so Article One has no bearing. The Kentucky primary is in May, and candidates file for a place on the primary ballot in January. Paul could file for the U.S. Senate and skip running in Kentucky’s presidential primary, and yet run in presidential primaries in other states.