There are few things in politics more worthless than a national, head-to-head, presidential poll more than five months before Election Day. That said, we have hit an ominous milestone for all those who think the GOP has handed the election to Hillary Clinton by nominating Donald Trump . If you look at the Real Clear Politics average this morning, this is what you see:

Your eyes do not deceive you; for the first time since pollsters started asking the question, Trump leads Clinton in an average of national, head-to-head polls. He has led in individual polls before, but never in the more reliable average of those polls.

Now, there are the usual caveats: We don't elect presidents by national popular vote ( not yet , anyway); a lead of 0.2 percentage points isn't much of a lead; the polls that went into the average still have the race within the margin of error; the Huffington Post's national-poll average still shows Clinton with a lead (albeit her smallest lead since early January). And there's one more important caveat: Republican voters, their race already over, have begun the process of rallying around the presumptive nominee, whereas Democrats still watching Bernie Sanders fighting for every last delegate have not.

Still.

The prevailing thinking among Democrats, I think it's fair to say, is that Hillary can start measuring the drapes in the White House because Trump is a) well underwater in terms of favorability with virtually every demographic; b) considered a boor, if not an outright racist, by many voters; and c) a political novice who may not hold up well in the long general-election campaign. The problem for her is that she is a) also widely unpopular; b) considered corrupt and untrustworthy by many voters; and c) someone who lost despite a sense of inevitability eight years ago and who has struggled to put away an old, white socialist in this year's primary.

In other words, it seems that Democrats have yet to reconcile themselves to the fact that many voters see this November's contest as an unappealing choice between undesirable candidates because their likely nominee is also deeply, deeply flawed. One of them is (probably) going to win despite their flaws. It might not be Hillary.

This might turn out to be the only day Trump leads Clinton nationally. He might hold a narrow lead, only to watch her numbers rise as she sews up the nomination and Democrats rally to her. Or this might be the beginning of something the way the soaring blue line in  this graph from mid-July 2015 was: