The point is Buchanan opposed Clinton trade policies (Free Trade, NAFTA), Gore trade policies and Bush 2 trade policies (CAFTA) which are all the same.
On the issue of trade it would be fair to say maybe the Republicans should nominate Gore, or maybe the Dems should invite Jeb to run on their ticket- BECAUSE THEY AGREE ON TRADE.
These Republicans and Democrats may agree on trade but they differ on a few other minor issues such as foreign policy, the war on terror, abortion, Supreme Court nominees, etc.
Maybe Buchanan thinks that trade is the most important issue but I don't.