The United States president nomination circus rolls into South Carolina for Republicans in a primary on February 20, and for Democrats to Nevada for caucuses. But after two rounds of voting in Iowa and New Hampshire, we can say that Hillary Clinton has a fight on her hands all the way to the floor of the Democratic Convention in Philadelphia at the end of July, and Vermont Senator Bernie Sanders will run her too close for comfort all of the way.

And on the Republican side, two rounds of voting have demonstrated that unless mainstream Republicans unite soon behind a single, electable candidate, their party’s leadership and presidential bid will be hijacked by the Right and the ridiculous in the form of either Ted Cruz or Donald Trump.

Should either of these actually win enough delegates at the Republican Convention in Cleveland, the week before Democrats gather, the politics of the US will never be the same.

The issue for Republicans is not that there’s no suitable mainstream candidate — there is. It’s just that he hasn’t emerged yet. Jeb Bush is staying in — he sees a potential opportunity. So too do John Kasich and Marco Rubio.

The decision of Chris Christie to suspend his race helps thin the field — and the others need to leave it soon, lest Cruz and Trump gain unassailable leads.

There is a reality too that even if a moderate, electable Republican does manage to unite the centrists, the damage done by Trump and Cruz will be too great for American voters to overlook come the presidential vote in early November.