Alot has changed over the years. For the past 20 years it has been the Christain conservatives who have whole heartedly supported Isreal. Although this began as far back with William Buckley, this is mostly because of Reagan who supported Isreal because he saw a thriving democracy in a region filled with filthy savages and bloody tyrants. Nothing has changed with the liberal country club Republican types though.
Conversely, the left has changed on Isreal as well. Democrats have increasingly supported more anti-American and anti-Western causes, exposing a the hidden anti-Semitism of the liberal elite that has been overlooked for a long time.