Perhaps Donald Trump is rewriting the rules of US politics. But let's not forget that's been said before and frontrunners often fade when the voting starts

Today, at last, we will finally start to see past the blarney and balderdash, the polls and projections, to see the outline of the US presidential race. The Iowa caucuses are being held and the voice of actual voters will get to drown out the voices of the candidates and commentators. For a while at least.

It seems that this has been an especially mad race so far, and it will be especially fascinating to see who gets the actual support of voters. And it's hard to argue that Donald Trump in particular and his frankly disgusting tactics are something unprecedentedly awful in US politics.

Yet it's worth remembering that wild card frontrunners are nothing new. It's easy to recall that Hillary Clinton herself was supposedly a lock just eight years ago, until a certain junior senator from Illinois changed that. Just four years ago that pizza CEO Herman Cain was leading the polls as late as November, followed by Rick Santorum and Newt Gingrich. Each fell away.

And remember Howard Dean leading the Democratic field in 2003/04?

There's a long tradition of such swings once voters actually start paying attention to the campaign as voting begins. Jimmy Carter and Bill Clinton were both outsiders and 'back in the pack' candidates for much of their first runs at the top job. But they got up to defeat those who were deemed frontrunners.

Trump, of course, has defied political gravity longer than most; his 'slip ups' haven't translated into a loss of support in the way Cain's personal life, Dean's whoop, and other vices (perceived or real) have. There remains the possibility that the anger and mischief American voters usually save for the early days of campaigns may have condensed this time into actual voting patterns. Perhaps Trump is the new normal; but let's not pretend that's been claimed before.

The evidence suggests that early frontrunners usually benefit from name recognition. And Trump has better name recognition than any politicians, perhaps save Clinton. He's also kept the outrageous comments coming at such a rapid rate that he's never been out of the headlines. But as voting begins, Americans have a habit of winnowing.

And another crucial point is the question of who turns out... not everyone who sepaks to pollsters bothers to vote, and the polls of past voters tend to be closer than the general ones (even putting Trump in second place).

So there are a lot of known unknowns and today we'll start -- but only start -- to see what happens to this year's bunch.

A lot can happen in the next few weeks. Iowa is a particular state with an odd process. Remember, in 2008 Mike Huckabee won for the Republicans and in 2012 it was Santrorum. It's quite a religious state that cares about rural issues.

It will be just as telling what happens in New Hampshire, South Carolina, Nevada, and then on Super Tuesday, March 1.

On the Democratic side, Bernie Sanders has a lot riding on the first two states, as the general wisdom is that Clinton has leads in South Carolina, Nevada and many Super Tuesday states, especially amongst black and Latino voters.

So I'm fascinated by what happens. But I'd add that I'm just as concerned about a Cruz presidency as I am a Trump one. Cruz's platform, while not getting the same international attention, involves a flat tax, "carpet bombing" Islamic State territory and standing firmly with Israel, building walls, repealing Obama's healthcare reform and doing sod all about gun control.

Today, more than ever, God bless America.