The former South Carolina governor Nikki Haley emerged from the last televised debate before the Iowa caucuses clearly Donald Trump’s strongest challenger for the Republican presidential nomination, boosted by the withdrawal of Chris Christie, the only explicitly anti-Trump candidate to register significantly with voters. Voting begins in Iowa on Monday, before New Hampshire stages its primary a week on Tuesday. Haley has closed on Trump in New Hampshire and has hopes of seizing second place in Iowa at the expense of the rightwing Florida governor, Ron DeSantis. Nonetheless, the Trump camp remains bullish as the Iowa vote looms after having maintained hefty leads in the polls for months. On Wednesday night, one senior aide said the campaign “couldn’t have scripted any better ourselves” events in the Des Moines debate, delighting in the spectacle of the former US president’s rivals slogging it out on the CNN stage while Trump – who continues to refuse to debate – took an easy ride at a Fox News town hall. “If you watched any part of the ‘JV’ debate this evening, you see two campaigns that are beating the living hell out of each other,” Chris LaCivita told reporters after Haley fiercely debated DeSantis, while Trump performed on his own elsewhere. “Then you have a Donald Trump commercial that shows up and he’s talking about Joe Biden … we couldn’t have scripted any better ourselves.” “JV” stands for “junior varsity” – a designation for college athletes below first-team standard. At Drake University, Haley said, “I wish Donald Trump was up on this stage” but spent most of her evening fighting DeSantis, regardless of Trump’s whopping Iowa lead. Fox gave Trump an easy ride. On a network which has paid $787.5m to settle one lawsuit arising from his stolen election lie and faces other such threats, the subject never came up. Nor did Trump’s legal problems arising from that lie, including 17 criminal charges regarding election subversion. Nor were Trump’s other 74 criminal charges, for retention of classified information and hush-money payments, high on Fox’s agenda. Tim Miller, a Republican operative turned anti-Trump activist and writer for the Bulwark, a conservative Never-Trump website, delivered a withering assessment of the Fox News town hall. Describing “one big primetime infomercial for the frontrunner”, Miller described Trump’s hosts, the “‘straight news’ reporters Bret Baier and Martha MacCallum”, sitting “beside the disgraced former president listening to his Catskills stand-up bit and giggling like a couple of undergrads after a 5mg weed gummy”. Trump did not avoid every pitfall. Seeking to thread a particularly tricky needle, he questioned the harshness of abortion bans supported by Haley and DeSantis. But he also crowed that “for 54 years, [conservatives] were trying to get Roe v Wade terminated, and I did it, and I’m proud to have done it”. The remark drew applause from the Fox audience but delight from Democrats, given how the supreme court’s removal of the federal right to abortion last year (actually 49 years after Roe, the ruling which guaranteed the right) and other attacks on healthcare rights have fueled Democratic wins at the polls. Up and down the ballot, abortion is set to be a key election issue this year. Tommy Vietor, a former staffer to Barack Obama, posted Trump’s remark to social media and said: “Biden campaign is going to feature this in about a billion dollars’ worth of ads.” DeSantis, meanwhile, has spent hundreds of millions on his campaign but is widely seen to be in deep trouble, needing a strong second in Iowa to avoid having to drop out. He also stood to lose more than Haley from Christie’s decision earlier on Wednesday to bring an end to his own campaign. The former New Jersey governor was the only candidate to run on an explicitly anti-Trump platform, regardless of Trump’s hold on Republican voters. Ending his campaign in New Hampshire, the libertarian-minded state on which he pinned his hopes, Christie said: “Anyone who is unwilling to say that [Trump] is unfit to be president of the United States is unfit themselves to be president of the United States.” Haley and DeSantis have begun to attack Trump as caucus day looms but not in strong terms and while still reserving their harshest fire for each other. Christie also had harsh if unscripted words for both his rivals, in comments apparently picked up by accident on a hot mic before his speech was streamed. “She’s gonna get smoked and you and I both know it,” Christie said, presumably referring to Haley. “She’s not up to this.” He also said: “DeSantis called me, petrified that I would –” before the audio cut out. The remarks, which CNN confirmed were directed at Wayne MacDonald, Christie’s New Hampshire campaign chair, pointed to harsh political realities. Haley is clear in second in New Hampshire and has been reducing Trump’s lead. Most polling indicates Christie supporters will now turn her way. But Haley remains well behind Trump, particularly in her own state, South Carolina, which will be third to vote. Campaign wisdom says candidates who cannot win their home state cannot hope to win over their whole party. DeSantis is well behind Trump in Florida and everywhere else. He would certainly have reason to be “petrified” that Christie’s withdrawal will ensure Haley becomes the only competitor to Trump with any notion of viability at all. The DeSantis and Haley campaigns did not immediately comment.