With help from an allied group that is airing television ads in Iowa, Mr. Rubio is seeking to raise doubts on the right about Mr. Cruz’s toughness on national security — a potentially fatal vulnerability, should Mr. Rubio succeed, amid heightened concerns about terrorism. More quietly, he is trying to muddy the perception that Mr. Cruz is a hard-liner on immigration, asserting that Mr. Cruz supports “legalizing people that are in this country illegally.”
.. Their stances on core policy issues are actually quite similar: Each toes the conservative line on taxes, abortion and guns. But they are making the most of where they diverge: Mr. Rubio’s more moderate posture on immigration, and Mr. Cruz’s effort to chart a middle course on national security between hawks like Mr. Rubio and more libertarian-minded Republicans like Senator Rand Paul of Kentucky.
.. And they are working to sow doubts about Mr. Cruz’s convictions on immigration, an issue on which Mr. Rubio is vulnerable because of his leadership role in the failed effort to push through legislation that would have offered a pathway to citizenship for undocumented immigrants. Aides to Mr. Rubio have quietly pushed reporters to question Mr. Cruz about how he defines amnesty — an effort to undermine Mr. Cruz with hard-liners by exposing his unwillingness to call for mass deportations.
.. Mr. Rubio, though, has a very different view of how the campaign is to be won. While he is stepping up his appearances in the early nominating states, his aides believe that garnering positive news coverage, especially in the widely viewed debates, is most crucial to early success, which then begets subsequent wins.
.. “More people in Iowa see Marco on ‘Fox and Friends’ than see Marco when he is in Iowa. Of course, that doesn’t mean you don’t go to Iowa.”