That's actually not quite true. The founding fathers varied greatly in their political beliefs. Ron Paul would have beliefs that are more similar to an Anti-Federalist. The Anti-Federalists did not agree with the constitution, because they thought that it gave too much power to the national government. They were the main force behind the addition of the Bill of Rights.
Take Alexander Hamilton, for example. He was a Federalist and one of the main proponents of the Constitution. He was also a war hawk and believed that the federal government should have unlimited military power.
You are obviously free to support whoever you wish, but do not make the assumption that anyone who is against Ron Paul is also against the Constitution.