After Nevada: Five (unlikely) ways Trump can still be stopped
There was one clear winner after Tuesday's Nevada caucus - Donald Trump.
The New York billionaire has emerged victorious in his third-straight nominating contest. He has come out on top in primaries in New England and the south, and he has now won a caucus in the west.
He is bringing voters to the polls who have never participated in the Republican political process before - voters who the political wags never thought would turn out.
He is appealing to hard-core Tea Party conservatives and born-again evangelicals; libertarian true-believers and blue-collar moderates. If caucus entrance polls are to be believed, Mr Trump even won Nevada Hispanics by a significant margin over two Cuban-American senators.
If Mr Trump is the winner, the rest of the field - no matter how it shakes out - are the clear losers. And they are losers who are running out of time to derail the growing Donald Trump juggernaut.
Can it be done? The odds are growing increasingly long, but here are five ways it might happen - and why it probably will not.
Marco the establishment man
Marco Rubio has secured the blessing of Republican officeholders across the nation.
He finished second to Donald Trump in South Carolina and could repeat the performance in Nevada.
But second place is first loser, as the saying goes, and he needs to find somewhere to break through and notch some wins before Trump becomes inevitable. Where does that happen? Even in his home state of Florida he trails the New Yorker.
How Trump is beaten: The Republican Party apparatus has picked its candidate, and consolidated support allows Rubio to pull ahead while Trump never breaks past 30-40%. Maybe the Floridian forces Kasich out of the race - either by promising him the vice-president spot or by appealing to his civic responsibility.
It takes Rubio a while to start winning primaries, but when he does the victories snowball into a wave that carries the senator to the nomination.
Why it does not happen: The establishment field is still somewhat fractured.
John Kasich seems stubbornly determined to stay in the race, and Ted Cruz likely pulls away some anti-Trump support that could be Rubio's.
Time is running short. Despite a strong effort in Nevada, Rubio could not get any traction. If he is going to make his move, it has to be soon.
Ted Cruz's southern revival
The momentum Ted Cruz had after his Iowa caucuses and second-place showing in New Hampshire has evaporated. He may have hoped his organisation in Nevada would allow him to be a surprise winner, but that was not to be.
As he said during his concession speech, next Tuesday, when a large slate of southern states vote, will be the "most important night" of his campaign.
How Trump is beaten: Cruz recaptures his magic thanks to a strong performance in his delegate-rich home state of Texas and across the South. Trump's air of inevitability is broken, and he falls back to the pack.
Why it does not happen: If there is a candidacy that is broken, it is Cruz's.
He has endured a string of bad headlines, including having to fire his chief spokesman after a social media scandal. With his win in South Carolina Trump has already shown he can thrive in the South - and he buries Cruz on Tuesday with across-the-board victories.
John Kasich's land of brokered dreams
Ohio Governor John Kasich did not even try to contest Nevada and seems ill-suited for the upcoming slate of southern primaries. Where he does have a chance, however, is in his home state of Ohio, which votes on 15 March.
Starting then, many of the states, including Ohio, are winner-take-all. That is where Kasich makes his move.
How Trump is beaten: If Kasich can nab all of Ohio's delegates and maybe pick off another Midwest state or two, he could garner enough support to deny Trump the nomination.
If no one has a majority of the delegates at the end of the primary process, there is a brokered convention where the presidential nominee will be decided by behind-the-scenes manoeuvring and deal-striking between the various candidate camps.
Why it does not happen: Kasich currently trails Trump in Ohio and across the Midwest. He has got little momentum and even less money. If he survives to 15 March, it will be only just barely. There has not been a Republican brokered since 1948 - ancient history in US politics.
Independents to the rescue
The editors of the Boston Globe suggested an interesting strategy for left-leaning independent voters in Massachusetts, where Trump currently holds a large lead over his Republican competitors. In the state's primary on 1 March, they said, even unaffiliated liberal voters should cross party lines and support one of Trump's opponents.
By picking someone other than Trump, they would keep the New Yorker's margin of victory down and deny him delegates.
How Trump is beaten: With Massachusetts voters leading the way, independents and even Democrats in states with open primaries flock to the polls to stop a candidate they view as toxic. That helps lessen Trump's advantage in new voters and tips the electoral scale to one of his opponents.
Why it does not happen: Some Democrats appear to be openly cheering for Trump to burn the Republican Party to the ground, figuring he will be easily defeated in the general election. Besides, the Bernie Sanders v Hillary Clinton battle is still going strong, and they might be more concerned with actually picking their party's nominee.
Trump finally implodes
Maybe, just maybe Trump finally says something so outrageous, so politically radioactive that it torpedoes his candidacy.
Perhaps there's a position so anathema to conservatives that even Trump cannot take it without alienating his voters. Or maybe there is a segment of the population the New Yorker just cannot insult without repercussions.
How Trump is beaten: Conservative voters shake their heads, as if emerging from a long slumber, and decide they do not want to support a brash, controversial businessman for commander in chief after all. There was a line out there, and Trump finally crosses it.
Why it does not happen: There is no line. This is not a dream. Trump may still be beaten, but he is not going to beat himself.