It took them long enough, but some Republican groups are finally attacking Donald Trump with TV commercials, online ads and mailers in the run-up to the Iowa caucus.
Within the anti-Trump wing of the Republican Party, however, strategists are divided over the most effective message to emphasize. Some Trump foes even see value in propping up the billionaire's popularity temporarily as a weapon to eliminate Ted Cruz, who they consider the more urgent threat.
Alex Castellanos, a Republican consultant who previously explored creating an anti-Trump PAC himself, actually castigated Trump critics in an open strategy e-mail on Monday for taking him on too soon.
"This contest is not yet about defeating Donald Trump, it is about finding an alternative to him," Castellanos wrote. "If that alternative is Cruz, the Republican Party's future is in doubt."
Others believe a coordinated assault on Trump is long overdue. In the last week, two newly minted anti-Trump organizations run by veteran GOP consultants have debuted modest web and radio campaigns targeting the front-runner.
Groups supporting Cruz are also hitting the airwaves in Iowa to go after Trump, who has savaged the Texas senator in interviews and speeches this month. This week, pro-Cruz super PACs Keep The Promise I and Stand For Truth unveiled new TV ads questioning Trump's conservatism.
"Extreme," one of the ads from Keep The Promise, features footage of Trump in 1999 on "Meet The Press" telling host Tim Russert that he's "pro-choice in every respect" and would not support a partial-birth abortion ban (Trump has since declared himself pro-life). "NYC," by Stand For Truth, features the 1999 clip as well as old footage of Trump praising Hillary Clinton and saying he lines up with Democrats.
Cruz has worked carefully to court Trump voters, and Kelyanne Conway, top strategist for Keep The Promise, told MSNBC that the ads were not meant to denigrate the billionaire or his supporters. One of their ads even features Trump lavishing compliments on Cruz in happier times.
"These are not nasty gratuitous personal attacks, these are contrast ads based on philosophical difference," Conway told MSNBC over the phone. "Even if [Trump] has had a change of heart - and we pro-lifers welcome all converts, he has failed to elevate the life issue."
Katie Packer, a veteran of Mitt Romney's 2012 campaign who is running the new anti-Trump group Our Principles PAC, also stressed the importance of undermining Trump's credentials with the right. Her group has sent out mailers in Iowa and produced a web ad highlighting Trump's past praise for single-payer health care, his previous call for a tax increase (he's running on a multi-trillion dollar tax cut this year) and the time he endorsed impeaching George W. Bush.
"There has not been a sustained message challenging Trump on the core conservative issues that have defined the Republican Party for decades," Packer said in an e-mail.
But some Republicans are skeptical that presenting Trump supporters with evidence of conservative heresy, which rival candidates have tried to do in debates and speeches, will work. They argue that the billionaire's appeal is rooted less in his ideology and more in his broad promise to stick up for the little guy.
"It's about strength and the idea that Trump is someone who wins," Kristen Soltis Anderson, an unaffiliated Republican pollster, told MSNBC. "Voters who feel tired of losing - economically, culturally, politically - are drawn to Trump despite his breaks with conservative principles."
Veteran GOP strategist Liz Mair, whose Make America Awesome PAC is running radio anti-Trump ads in Iowa, says her focus groups also showed that this approach was the most effective one.
"If people know he's not their champion and is the guy who's been screwing people like them over, it's a problem for him," Mair texted MSNBC.
Mair's group does have an ad highlighting Trump's position on heath care, but another spot, titled "Real Trump Record," focuses almost entirely on his business career. It references a report in Forbes claiming Trump's net worth is exaggerated, his companies' repeated bankruptcies, his comment in a debate that American wages are too high to attract jobs and his businesses' reliance on imported workers.
"That's the real Trump record: Fighting for himself - not for us," the ad ends.
Cruz has adopted some similar tactics himself. He recently unveiled a new campaign ad highlighting Trump's attempt to seize a woman's property through the courts and build a parking garage over it for a casino. The ad is about eminent domain, which many conservatives oppose on philosophical grounds, but it's also an excuse to tell voters a story about a ruthless billionaire targeting an elderly widow to pad his profits.
There is another possibility, though: Trump may just be impervious to attacks of all kinds. The political graveyard of failed 2016 contenders is littered with candidates like Bobby Jindal and Rick Perry who tried and failed to refocus their campaign on bashing Trump and the current contenders have mostly turned to other battles.
With the exception of Cruz, who ironically maintained a careful truce with Trump until just last month, candidates and their allies are focusing their own efforts on tearing down rival candidates that occupy a similar space in the party: Jeb Bush, Marco Rubio, John Kasich, and Chris Christie are targeting each other while Mike Huckabee and Rick Santorum are going after Cruz. Anti-Trump Republicans like Packer have excoriated groups like the pro-Bush Right to Rise PAC for dumping tens of millions of dollars into attack ads against candidates like Rubio while leaving Trump unscathed.
Maybe Republicans like Castellanos and those advising the candidates are playing three-dimensional chess and the proper play is to let Trump romp in the short term to secure victory in the long term. But a week from Iowa, polls show Trump leading in every single early caucus and primary. If he ends up winning the nomination, expect to hear a whole lot of Republicans wonder aloud why they didn't react sooner.
This article originally appeared on MSNBC.com.