The less alarmist experts I've read are all pointing to the fact that, historically, a huge poll lead for the primaries at this point means very little. There have been quite a few Republican candidates with large poll leads at this stage who most of us would probably struggle to remember.
Many are also pointing out that those polling for Trump are not traditional voters and that it's hard to estimate how many will turn up this time.
On the downside (for those of us who are not Trump fans), there's a lot of in-fighting between the other Republican candidates and it currently looks unlikely that they'll all gather behind one candidate. I can't see that lasting though, I imagine most would want a good position behind another candidate rather than scrap to the end. They'll only do this if they think their candidate can win the presidential elections though and I don't think that most Republicans think Trump or Cruz can do that.
In Trump's favour when it comes to a presidential election, is that people are currently scared and scared people do change the way they vote drastically (insert neat side-stepping of Godwin here). There's also the fact that, for all his great social policies, Sanders has some pretty far out economic ideas - some of which would be considered fairly left wing on this side of the pond. Clinton is just a fudgewit and I suspect that if she wins the nomination there will be a huge pile of confidential email leaked from her private account that has been held back for later use. They'll also bring up her "struggles with the truth", which are numerous even for a politician.
Looking at who is available, it's not a great time to be an American. In terms of knock-on effects for the UK, I'm hoping for either a moderate Republican or a puppet Clinton kept well away from anything she can do damage to or with - that's about the best we can hope for.
