Sean Hubbard

Of the six top-tier candidates running for the U.S. Senate, only Sean Hubbard may have to worry about being challenged by eagle-eyed poll watchers, suspicious that he is too young to vote. Fresh-faced and slight, the Dallas resident is 31, but looks half that.

The young Democrat likes to remind audiences that Joe Biden was 29 when he was elected to the U.S. Senate from Delaware, and like the current vice president, Hubbard is articulate, engaging and well-versed on the issues.