Even Reagan understood that Keynes was fundamentally right. When defending Nixon’s failure to implement austerity in a recession he said:
“Could the president, in the economic dislocation that accompanied his anti-inflation fight, and the transition from a war to a peace-time economy, shut off spending by the world’s biggest buyer of goods and services (the US government) without risking a full scale depression.” from Reagan in His Own Hand (Just “search inside” for “Keynesian”.)
Reagan was fully aware that this was Keynesian economics, but argued is was not the over-done version of the Dems. He was always careful to spin everything, but he was perfectly clear that Keynes’s main point was correct. (The quote above was hand-written by Reagan.)