On the Democratic side, a potentially historic clash lies ahead. For the GOP, Michigan is the next test.
Caucus results shake up the race for the White House in both parties.
Most polls show a very close race among the top candidates in both parties, so the outcome hinges on which campaigns are best at turning out their supporters.
Veteran pollster finds Huckabee and Romney neck and neck in Iowa, while Clinton's lead shrinks in the Granite State.