It is beyond dispute that Donald Trump has the momentum in the presidential race. It is also beyond dispute that he still has an in­cred­ibly narrow path to get to 270 electoral votes to win the presidency.

Let’s start with the two most important numbers in this election: 18 and 13.

Eighteen is the number of states every Democratic presidential nominee has carried in each of the past six presidential elections, dating to 1992. Add in the District of Columbia, which also fits the bill, and you get 242 electoral votes.

Thirteen is the number of states every Republican presidential nominee has won in those same presidential elections. Add them up, and you get 102 electoral votes.

You do not have to be a Fields Medal winner to quickly grasp Republicans’ problem: Their party starts in a significant electoral-college hole, fueled by several states with large populations — California, New York and Illinois, to name three — that are among the most reliably Democratic in the country.

Democratic presidential nominee Hillary Clinton spoke at the Congressional Hispanic Caucus' awards gala where she took aim at rival Donald Trump, saying that Trump spews "bigotry and hate." (Victoria Walker/Photo: Melina Mara/The Washington Post)

That problem existed before Trump was even a glint in the eye of Republican voters. And it is likely to exist well beyond whatever happens to Trump on Nov. 8. But what it means in practical terms is that even as the race has tightened at both the national and swing-state level, Clinton retains far more paths to 270 electoral votes.

Consider this: If Clinton wins the 18 states plus the District that every Democrat has won since 1992 and also wins Florida (and its 29 electoral votes), she is president. If Clinton wins those 18, the nation’s capital and Ohio (18 electoral votes) and Virginia (13 electoral votes), it’s over.

There are lots of other ways for Clinton to get to 270 or beyond. But what’s more instructive is to look at the paucity of routes Trump has to reach that same number.

Start with an assumption that Trump wins every state that Mitt Romney did in 2012. (That’s a bit of a stretch, given that polling in North Carolina, Arizona, Georgia and Missouri — all states that went for Romney — suggests tight contests.)

If we assume that, Trump starts with 206 electoral votes. He needs at least 64 more.

To understand just how narrow his path is, give him Ohio, Florida, Nevada and Iowa. Under that map, he still loses to Clinton — 273 electoral votes to 265.

Trump, realistically, has only three paths. (And, by “realistically,” I mean within the realm of conceivable. Yes, of course, Trump could run the table of swing states and win easily. But there’s little indication that will happen.)

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1. Win Pennsylvania. If Trump could turn the Keystone State, which is one of the 18 “Blue Wall” states that have voted Democratic in each of the past six elections, then the map opens up for him. Subtract 20 electoral votes from Clinton’s presumed 242, and it forces her to add 49 electoral votes rather than just 29.

2. Win Ohio, Florida, Nevada, Iowa, and Colorado or Virginia. Colorado and Virginia have been swing states for at least the past two elections and, in Colorado’s case, far longer. But Trump’s struggles with nonwhite voters have badly complicated his chances in both states. Clinton’s campaign and its aligned super PAC ceased advertising in both states a month ago — a sign of their confidence about her prospects. Trump continues to spend on Virginia, suggesting that he sees a chance in the Old Dominion.

3. Win Ohio, Florida, Nevada, Iowa and New Hampshire. That scenario gives Trump 269 electoral votes and Clinton 269 electoral votes. If that happens — and it’s not impossible, by any means — then the election would be thrown to the House of Representatives, where each state would cast a single vote for president. Such an outcome would invalidate Democrats’ electoral-college edge; Idaho would have the same amount of sway to choose the president as California.

None of those three scenarios is outlandish. But they all require Trump to not only consolidate the gains he has made over the past few weeks but also to expand them. His recent surge has brought him back into contention. But it has not vaulted him ahead.

The task before him is the equivalent of threading a very narrow needle with 300 million people (or so) watching. That’s possible but far from likely. Still.