The Case for, and Against, Marco Rubio as Republican Presidential Candidate

In the early 2016 Republican presidential jockeying—as the field of potential candidates grows, and as Jeb Bush, Mitt Romney, Scott Walker and Rand Paul grab the recent headlines—an interesting development is unfolding just beyond the limelight: In the eyes of many in the party, Florida Sen. Marco Rubio has quietly moved into the upper tier of that long list of potential candidates.

He gave a well-reviewed performance at a recent gathering of donors organized by the conservative Koch brothers. He has raised eyebrows by...