WASHINGTON, Aug 21 (Reuters Breakingviews) - Like Richard Nixon going to China, sometimes a change in policy is sold best by an unlikely proponent. Vice President Kamala Harris leading the charge for more housing supply in the United States shows just how far her party has come. Democrats have long been skeptical about overhauling supply and regulation to make housing more affordable. Harris’ $40 billion housing agenda, released last week, is a welcome recognition that drastic changes are needed to close a national shortage of 4.5 million homes.