SENATOR Marco Rubio of Florida, a young Cuban-American with a stirring, up-by-the-bootstraps life-story, was once called the future of the Republican Party. His poor showing in a series of presidential nominating contests held on March 5th—including a fourth place in the New England state of Maine—leaves his campaign for the White House running on fumes. After Republican presidential primary elections or caucuses in 19 states, Mr Rubio has a win in just one, Minnesota, to his name. His last hopes rest on his home state of Florida, whose large haul of delegates is up for grabs on March 15th, though he is lagging in opinion polls there. Mr Rubio ticks many boxes on the lists that conservative donors, Republican strategists and pundits draw up when looking for winners. He is Hispanic and has spoken movingly of his sympathy for immigrants, but is conservative enough that he was elected to the Senate as a Tea Party hero. He can be sunny, upbeat and funny on a good day, but is also a disciplined candidate (to the point of extreme caution). He entered the 2016 race with a plan: to be the candidate who appealed to Establishment types and voters focused on electability and an optimistic vision for the future, while staying far enough to the right that he would not anger ideological purists.

Alas for Mr Rubio, his straddling strategy increasingly looks like a stretch too far. He is distrusted by the hard-right, who call him a backer of “amnesty” because he once worked with a cross-party group of senators on immigration reform. At the same time he has fallen short with mainstream, college-educated and white-collar Republicans, who have watched him harden his tone and portray the country as a dystopia on the brink of doom in a bid to catch the front-runner, Donald Trump, and his rival Senator Ted Cruz of Texas. Damagingly, as his support ebbed in recent days, Mr Rubio indulged in the sort of schoolyard abuse for which Mr Trump is notorious, mocking the billionaire’s “orange” sun-tan and seeming to question Mr Trump’s manhood. Talk-radio hosts have been bashing Mr Rubio for days, and suggesting that Mr Cruz is the only bet for Republicans anxious that Mr Trump has broken with conservative orthodoxy on such issues as abortion, gay marriage or government-funded healthcare.

Mr Rubio’s wretched March 5th coincides with a good night for Mr Cruz, who won caucus contests in Kansas by 25 percentage points and Maine by 13 points, and came a closer second than expected to Mr Trump, who won in Kentucky and Louisiana. A bumpy night for Mr Trump looks all the more turbulent because exit polls suggest that he did best among voters who cast ballots some days ago, and less well with those who turned out on election day. That will encourage Stop Trump forces within the Republican Party, who hoped that the New York property tycoon would be damaged by recent controversies and policy reversals. These include his muddled and initially equivocal response to praise from a white supremacist veteran of the Ku Klux Klan, and a double flip-flop over torture, when he seemed to say that as president he would order torture in defiance of international law, changed his mind to say he would heed the law and then changed it again to say that laws against torture needed loosening. Less cheeringly, many Trump supporters were probably most dismayed to hear their hero say in a TV debate that his current views on immigration, including a promise to deport 11m people without legal papers, would become more flexible in office.

Alas for Stop Trump leaders whose main concern is picking a candidate with general election appeal, their headaches are not eased by Mr Cruz’s rise. The Texan senator may be more polished than Mr Trump, and more of a conventional conservative. But he lacks Mr Trump’s astonishing ability to excite apolitical voters who want a champion to punish America’s foes and punch the ruling classes in the face. Mr Cruz is essentially a rigid ideologue whose plan for victory involves driving up turnout among exceedingly conservative and evangelical Christians. Mr Trump called on Saturday night for Mr Rubio to drop out to make this a two-man race, saying: “I want Ted, one-on-one.”

Even devoted Cruz fans are unsure whether their hero can overtake and beat Mr Trump in a straight race for delegates ahead of the Republican National Convention in July. Some would like Mr Rubio to drop out, along with the fourth-ranked candidate still in the race, Governor John Kasich of Ohio. But Mr Rubio and Mr Kasich have little incentive to drop out before the contests in Florida and Ohio, their respective home-states, in just over a week. Other Cruz backers wonder whether they need to keep the field large to split the vote in the remaining states and deny Mr Trump a clear majority of delegates, so that the nomination has to be decided in a bruising battle at the convention.

The picture on the Democratic side is growing clearer. Senator Bernie Sanders of Vermont, a left-wing populist, won caucus contests in Kansas and Nebraska, both mostly white, conservative states with small, embattled populations of leftish Democrats, many of them clustered in college towns. Mr Sanders lost the primary in Louisiana, where Hillary Clinton, the front-runner, retained her dominance among black Democrats. The snowy-haired, self-described democratic socialist has done far better than anyone expected him to when he first challenged Mrs Clinton, but his path to the nomination is now extremely narrow. The Vermont senator’s core support remains limited to very liberal whites and young activists, and there are not enough of them to power him to the Democratic nomination.

The clearest conclusion of all is that continued Republican chaos suits Mrs Clinton. Team Clinton calls Mr Cruz the easiest opponent to beat in the general election of November, with the narrowest nationwide appeal. Democrats close to the former secretary of state and first lady insist that Mr Trump is eminently beatable, and call him especially vulnerable among women thanks to his record of bullying misogyny. But they do not dismiss the billionaire out of hand, noting how he has upended assumptions about the race so far. The March 5th contests leave Mr Trump hurt but still dominant, like a bee-stung bull elephant, and guarantee that the Republican Party’s internal strife will continue for months to come.