The 30-second television spot from Keep the Promise suggests Rubio is not ready to be the commander in chief.
 
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"What would Marco Rubio's leadership look like?" the ad asks, before cutting to video of a smiling Rubio talking on the phone while staring at a laptop.
 
"Yeah I know I have a debate, but I got to get this fantasy football thing right," Rubio says in the video, originally released by his campaign in a spoof of his preparation for an October debate.
 
"Tell Marco Rubio: America can't afford to gamble with its safety," the Cruz ad then states.
 
Rubio's campaign hit back at the video, with an aide tweeting, "Wonder which Cruz-Simpson character @tedcruz PAC thinks is best prepared to lead the country?" and linking to a video of Cruz doing impressions from "The Simpsons."
 
Cruz leads polls in Iowa, while Rubio is in the upper tier of candidates in all of the early-voting states, according to polls.
 
The video is part of a $1 million advertising blitz by the Cruz super-PACs, running for two weeks starting Tuesday in Iowa, according to a representative from the group.
 
Those behind the TV ad say it will be released digitally in other early-voting states, including New Hampshire, South Carolina and Nevada, along with radio ads hitting Rubio on immigration.