As the Iowa Caucuses near and the Republican presidential field enters cage-match mode, there has been some movement in "the three lanes" — the social conservative lane, the establishment lane and the Donald Trump lane — within the party, and according to the latest NBC News/Wall Street Journal poll the GOP frontrunner is the biggest beneficiary.
Voter groups that have long supported the GOP's main establishment candidates are beginning to peel off to join other candidates, particularly Trump.
Between December and January, Trump saw a five-point increase in support from tea party voters. At the same time, the "establishment lane" saw a five-point decline in tea party support. In the social conservative lane, meanwhile, it looks like voters simply moved from Carson to Mr. Cruz.
