In 1968 Newt did join the Rockefeller campaign, and he did campaign as a liberal in the early 70's, according to two liberal websites that BSB linked to. I assume that information is correct.
Once elected to congress in the mid 70's, though, Newt did join with conservatives and did have a ACU lifetime rating in the 90's. Not just join but he actually has been a conservative leader over the past 30 years. And I have no doubt he would govern that way if elected president. He does have significant achievements under his belt, like balancing the budget as Speaker of the House and helping to bring unemployment down to under 4%. Those are very much needed now.