I doubt Ron Paul will endorse Romney:
One is a statist, the other for liberty.
One is a Keynesian (central planning), the other is of the austrian school of economics (free market).
One is for wars, the other is for peaceful coexistence when possible.
One supports the bailouts, the other thinks it is robbery of the people.
One thinks government can create jobs by confiscating capital, the other thinks jobs are created by businesses when the government leaves them with enough capital.
One is a supporter of the Federal Reserve, the other thinks the Federal Reserve is the cause of economic distress.
One is Alexander Hamilton, the other is Thomas Jefferson.