Before Donald Trump came along, Bill Kristol exemplified virtually all the leading elements of the modern Republican Party. After watching his father help found the neo-conservative movement, he joined the Reagan Administration as an aide to Education Secretary William Bennett, a leading figure on the cultural right. Later he pressed President George H.W. Bush from the right on taxes and other issues as chief of staff to Vice President Dan Quayle.   In 1993, at the newly-minted Project for the Republican Future, he helped direct the party’s successful effort to block President Bill Clinton’s health-care plan. He launched the conservative magazine The Weekly Standard and became a commentator for Fox News. He staunchly backed President George W. Bush’s Iraq War and promoted Sarah Palin for the vice presidency in 2008.   Now, at 65, Kristol has made a radical break. Alarmed at Trump’s policies and his methods, he has become a leading voice of Republican opposition. That has damaged old friendships and made new ones; Kristol now offers analysis on MSNBC. He is re-examining old assumptions about fellow conservatives and Republicans – and contemplating new possibilities for progress in the political center.   We talked over beers at the Mayflower Hotel near the White House – the same hotel where he and others decided a quarter-century ago to launch the magazine he still serves as Editor-at-Large.