Fear and hatred stalked the Republican debate on Saturday night, aimed at every available target, including, as starkly as ever, the immigrant threat.  Donald Trump took credit for raising the alarm first — “Now everybody’s coming to me,” he said. Senator Ted Cruz boasted that his immigration solution was the most detailed — “11 pages, single-spaced” — though it focuses so intently on criminalizing unauthorized immigrants that it seems more like a blueprint for keeping millions of people in prisons, rather than sending them out of the country.  The candidates kept summoning President Ronald Reagan, whose 105th birthday it was. If only Reagan’s ghost had risen up and driven everybody from the stage, to uphold his vision of a welcoming America that his party has abandoned.  Only Gov. John Kasich and Senator Marco Rubio tried to be hard-line without the hate. Mr. Kasich said, again, that deportation of 11 million people is unrealistic, a statement of simple fact that in this context counts as bravery.  Mr. Rubio was ridiculed, again, for helping to lead Congress’s last push for big immigration reform, in 2014 — and for later disowning it. Mr. Rubio actually does defend the bill, in the most timid way, by slipping its tough parts into his stump speeches and debates. When he calls, fiercely, for 700 miles of border fence, mandatory employment verification and an entry-and-exit visa system, he does not tell crowds that President Obama and the Democrats were good with that, too.  Mr. Rubio also leaves the door open for better things, like legalization for the unauthorized, someday. If you believe what he says sometimes — often in Spanish, to immigrants who plead with him for help — and his vow to unite the party, it almost sounds like he means it.  Watching him campaign in New Hampshire, with speeches full of hope, humor and self-deprecation, it was possible to imagine the party actually winning back a few Latino voters. That, plus massive voter suppression, could improve the odds for the G.O.P. in November.  Mr. Rubio’s odd behavior on Saturday may have changed things. It started when Gov. Chris Christie basically called him a robot, and just then — wouldn’t you know it — Mr. Rubio’s software malfunctioned. His page didn’t load; he kept repeating some strange lines about how dangerously, tragically transformative President Obama has been. A New Hampshire newspaper, The Conway Daily Sun, saw this coming last December, when Mr. Rubio visited: “It was like someone wound him up, pointed him towards the doors and pushed play.”  This is deflating news. Republican voters need Mr. Kasich and Mr. Rubio to survive down the road, like the man and boy in that Cormac McCarthy doomsday novel, to keep alive the flame of decency toward the foreign-born.  The Democrats are dispiriting in a different way. Hillary Clinton and Senator Bernie Sanders have strong immigration platforms, but they haven’t been touching the issue lately. There are questions they need to answer. What if the Supreme Court kills President Obama’s executive actions on deportation and work permits? How will you repair the damage of Mr. Obama’s deportation strategy? How will you revive comprehensive reform, and who will slay the Republicans’ nativist dragon?  Immigration, the debate, is in a bad place. But immigration, the reality, is still changing and challenging America. New Hampshire could do its part on Tuesday. Mr. Trump seems poised to win here, as he is everywhere. But the state still is habitat for the endangered moderate Republican, like Fergus Cullen, a former state party chairman who founded an immigration-reform group, Americans by Choice, which offers pro-business arguments, but hasn’t been heard from much lately. Voters there could stand up for the non-nativists, the way they elected, barely, Jeanne Shaheen, the rival of Scott Brown, who ran for Senate warning of immigrants bringing Ebola into Texas.  There is a long list of things Americans are terrified of; immigrants should not be on it.
The candidates who debated on Saturday repeated their warnings about immigration, and unfortunately one of the less extreme candidates, Marco Rubio, stumbled at the event.