Boone, Iowa — On a frigid, gray morning, Rafael Cruz’s unnamed target was as evident as his message touting his son’s principles as he addressed some two dozen Ted Cruz supporters in a basement room of a converted livery stable.

“Don’t listen to the rhetoric,” the elder Cruz pleaded. “Slogans didn’t build America.”

His comments — and more direct comments by Cruz and other surrogates — reflect the fact that, in the weeks before next Monday’s Iowa caucuses, Donald Trump’s onslaught of criticism has halted the Texas senator’s eight-month rise from conservative outsider to Hawkeye state favorite.

And this small but intense group — one of dozens of caucus training sessions the Cruz campaign has convened — represents the traditional organizational effort that the meticulously organized Cruz campaign hopes will blunt Trump’s effort to capture the caucuses by stirring excitement through highly publicized large rallies.

Later that same day, at a raucous rally at Faith Baptist Bible College in Ankeny, commentator-turned-Cruz-backer Glenn Beck succinctly spelled out the stakes:

“If Donald Trump wins (in Iowa),” Beck said, “it’s going to be a snowball to hell,” perhaps providing him unstoppable momentum toward the GOP nomination. That would undercut Cruz’s plan to ride Iowa success into the bigger states, especially in the South.

“Cruz has run the most focused campaign,” said GOP consultant Alex Castellanos, no supporter. “He’s raised an exceptionally large sum of money. He’s built the best ground game and the most powerful social media operation.”

And he benefited from the cratering of rivals for the votes of evangelicals crucial here and in South Carolina: Wisconsin Gov. Scott Walker, and former Govs. Rick Perry of Texas and Bobby Jindal of Louisiana withdrew; prior Iowa winners Mike Huckabee and Rick Santorum failed to rekindle past support; and Ben Carson faded after weak debate showings.

But polls suggest Trump’s endorsement by Sarah Palin, whose backing Cruz credits with his Texas Senate victory, might cost Cruz among evangelicals.

And Trump’s invective not only forced Cruz onto the defensive but revived some issues that prompted initial doubts about his chances.

While polls indicate few Republicans seem concerned about Trump’s harping on Cruz’s Canadian birthplace, his assertion that “nobody likes him” has reverberated among establishment Republicans.

“I don’t know how he’s going to work with Congress,” echoed longtime Kansas GOP senator and 1996 nominee Bob Dole. “Nobody likes him.”

Others liken his doctrinaire conservatism to former Arizona Sen. Barry Goldwater, who pulled the GOP sharply right in 1964 and lost 44 states, dooming dozens of other Republican candidates.

“The fact is, when Barry Goldwater lost, (Republicans) lost big-time,” Sen. John McCain, R-Ariz., told a Christian Science Monitor breakfast last December. McCain once called Cruz and fellow hopeful Sen. Rand Paul, R-Ky., “wacko-birds.”

Cruz supporters dispute that comparison. “The electorate has been so abused the last eight years, they’re going to see that the alternatives are a corrupt politician (Hillary Clinton) or a socialist U.S. senator (Bernie Sanders) and someone who is principled,” said Aaron Cronk, 38, a stay-at-home father and Boone County co-chair for Cruz.

To counter Trump’s attacks, the whirl of his publicity and attacks in television ads, Cruz is relying on that old Iowa standby, organization.

The stress here and at similar sessions was on making personal contact with family, friends and neighbors. Each local Cruz chair will receive this week a list of all who support the senator in his precinct.

Eight years ago, though, Barack Obama won the Democratic caucuses by flooding them with new voters, many young. Trump hopes to replicate that, and a mild weather forecast might encourage it.

But the Cruz campaign believes many won’t take the trouble to turn out. If that happens, his organization may yet carry the day.

— Carl P. Leubsdorf is the former Washington bureau chief of the Dallas Morning News.