So Sarah Palin has endorsed her fellow reality television star, Donald Trump, for president.

It may not be a sign of the apocalypse, but the announcement is certain to keep the media and pundits busy for at least 24 hours.

At the very least, that helps Trump stay ahead in his Red Queen’s race — that is, his attempt to maintain his domination of political news, which makes it harder for any other candidate to move up.

It’s even possible that a handful of Iowa tea party voters who have been wavering between Trump and Ted Cruz could be swayed by the Sage of Wasilla. And who knows?

In a very close election, just a few voters could make all the difference: Trump and Cruz are in a dead heat in Iowa, according to HuffPollster’s current estimate.

On the other hand, there is no suggestion from polling that Palin’s endorsement is the gold standard. And although endorsements may be quite important in aggregate, the support of any single figure usually makes little difference.

Endorsements bring resources, whether it is publicity, money or volunteer hours. Palin will help with publicity for one day, but probably not much more than that.

It’s even possible, as political scientist Brendan Nyhan suggests, that Palin could push undecided party actors farther from Trump. After all, if the nomination really does come down to Trump against Cruz, it is going to be a tough choice for many party elites, especially those who have worked with Cruz and can’t stand him. Knowing that going with the Texas senator will at least have the benefit of annoying Palin may help to get them over that hump. In any case, having Trump out on the hustings praising Palin will remind many party actors of the weakness of his attachment to the party and of how little they can trust him either as their nominee or as president.

Mostly, however, this is just a reminder of John McCain’s irresponsibility in selecting Palin as his running mate without bothering to find out who she was. She now is repaying the 2012 Republican nominee by endorsing the man who attacked his unimpeachable heroism to climb to the top of the polls. Whatever happens next, Republicans should never forgive him for that.

Jonathan Bernstein is a Bloomberg View columnist covering American politics