Cruz Super PAC launches predictable but powerful attack ad on Marco Rubio's past support for immigration amnesty

Political scientists will spend decades debating why TV commercials during the 2016 GOP Primaries have become so ineffective as a means to persuade voters. Every cent has disappeared down a sinkhole. Just ask Jeb Bush, who has spent about a third of the total $111 million spent on TV and radio spots so far, and he is polling within the margin of error of zero.  (About this point in the cycle in 2012, according to ad tracking data from SMG Delta, the combined spend was a meagre $35 million).  

That's not to say there haven't been some good ads (none of them Jeb's), but the days of blanketing the airwaves with huge ad buys and watching poll numbers climb are over.  

If any ad will land a blow, it might be this one from Ted Cruz's Super PAC, targeting Marco Rubio on his past support for immigration amnesty.  Look at the juxtaposition of images – especially the extended cameos of Obama and the liberal New York Senator Chuck Schumer (cousin to Amy!) who has replaced the late Ted Kennedy as the go-to leftie bogeyman on the American Right.   

This ad doesn't MAKE Rubio vulnerable on the immigration issue – it has loomed over his campaign from the outset like a giant looming thing – but it may serve as a powerful reminder to GOP primary voters that the Florida Senator has a soft spot for "illegals".  Could hurt him.  Then again, like every other ad this cycle, it may just as easily sink without a trace.