“What you’re seeing is the clearest evidence of how wide open the center-right lane of the caucus electorate is in Iowa,” said Matt Strawn, a former Iowa GOP chairman who is uncommitted. “Those are all candidates that would love to get some momentum that will help them make their case in New Hampshire.”

“Both Bush and Christie see Rubio as the front-runner in that lane, and they’re trying to take him down so they have a better shot at it,” said Douglas Gross, who served as Mitt Romney’s 2012 Iowa finance chairman but, like a number of establishment conservatives, remains uncommitted.

The substance of the attack on Rubio not showing up to vote may matter less to establishment Republicans in Iowa, who are still trying to determine whether the young first-term senator is truly the GOP’s best general-election candidate. “I keep hearing that Rubio is people’s favorite among [choices Rubio, Bush and Christie] not because they love his voting record but because they think he’s the party’s best shot to beat Hillary Clinton,” Gross said. “So the other candidates really have to attack that electability narrative if they’re going to bring him down.”

But the absenteeism takedown has a chance of resonating in New Hampshire, where it runs parallel to recent stories about the Florida senator’s relatively light campaign schedule being a particular affront to an electorate that relishes its first-in-the-nation responsibility and demands accessibility from candidates.