IOWA CITY -- "Have you seen this?" asked a campaign aide for Sen. Ted Cruz (R-Tex.). He held up a smartphone with a photo of a mailer that Sen. Marco Rubio (R-Fla.) was bombarding Iowans with -- an "Iowa caucus report card," listing how many of the last four caucuses the recipient had been able to vote in.

A mailer sent out by Marco Rubio's campaign, captured by Ted Cruz's campaign. (Rick Tyler/Facebook)

The audacity took Cruz's team by surprise. For 24 hours, Rubio and other Republican rivals in Iowa had been condemning a Cruz mailer designed as a warning of possible "voter violations." Donald Trump called it "dishonest and deceptive," and suggested (incorrectly) that Cruz was under investigation. Sen. Rand Paul (R-Ky.), who is stubbornly taking libertarian voters whom Cruz wants, called it "kind of creepy" and reminiscent of "a lot of the stuff I don't really like about government."

Today, as the candidate barnstorms eastern Iowa, his campaign is pushing back by asking where Cruz gets off. Former Iowa secretary of state Matt Schultz, Cruz's state chairman, who had given a plaintive radio interview apologizing to voters offended by the mailer, told The Washington Post today that Rubio wanted to have it both ways.

"It's kind of bizarre to go out and attack us for something you're intending to do yourself," said Schultz. "It's just typical of Marco, wanting to be on every side of an issue. I've seen similar mailers in other parts of the country. I've read the social science. So it's just bizarre, in Marco's words from the Sunday shows, to act offended."

Rubio's campaign, which has gotten plenty of support on social media over the mailer story, pointed out that the "report card" mailer -- the Cruz campaign smoking gun -- was provided to media outlets. The generic version had been given to Time magazine's Zeke Miller for a story about how Rubio's version of the "social pressure" pitch did not trip the same wires as Cruz's.

"We've been sharing our mailer with press as a contrast to Cruz to prove our point," said Cruz spokesman Alex Conant. "We didn't single out specific voters."

The idea of telling reporters to vote by showing them how frequently their neighbors voted had been pushed by political scientists for nearly a decade — one reason the backlash has surprised Cruz's campaign. And according to Chris Larimer, a University of Northern Iowa political scientist whose 2008 work on "social pressure" inspired umpteen mailers like this, the Rubio piece was not as risky as the Cruz piece. Where Cruz's mailer suggested that voters might be violating a state standard if they failed to vote, Rubio's simply nudged them to turn out.

"The language is less confrontational than the Cruz mailer, but I still don't understand the use of caucus turnout vote history," said Larimer. "As I said yesterday, that information is kept private by the parties, so it would be interesting if the campaign is making it public."
The neighbor information stirred more confusion after political strategist Sarah Rumpf reported on the Cruz mailer. Dale Peterson, a professor at Iowa State University, showed Mother Jones reporter Pema Levy a mailer that gave him a 55 percent turnout score, even though he'd voted in five of the past six elections.
That led Peterson to ask whether the "data" was fudged to look especially scary, a concern he repeated to the New Yorker's Ryan Lizza, who could not get the campaign to discuss its numbers. Today, campaign spokesman Rick Tyler also ignored a question about the data, and Schultz could not say whether the data was accurate.
"My understanding is that it is," he said. "I don't know -- I haven't looked at it."
The fracas over the mailer has intensified the battle between Cruz and Rubio, with supporters of the Texas senator more convinced than ever that the media is trying to goose the news cycle for the Florida senator. In a short conversation at Cruz's Iowa City rally, Rep. Steve King (R-Iowa) laughed at the growing narrative that a caucus result that mirrored the results of the Des Moines Register/Bloomberg Politics poll -- a strong third-place showing for Rubio, second place for Cruz -- would amount to a Rubio "win" in Iowa.
"I have known for a long time that Fox News is very enthusiastic for Marco Rubio," said King. "So when I hear those things, I know it's just spin. I think Senator Cruz wins this in a close race."