"Pay no attention to the man behind the curtain."

That, apparently, is the new Trump campaign slogan, as the candidate attempts to slink away from his central policy promise, the forced deportation of 11 million undocumented immigrants. Pinched between true believers and crumbling polls, the GOP nominee is trying to remain the Great and Powerful Trump while tearing down the border wall he built his campaign on. That waffling has revealed that just like Oz, Trump is little more than a humbug, a flimflam man at the end of a long con.

Trump no doubt thought he'd found easy marks. For the past decade, the Republican base has been in open revolt against the party's stance on immigration reform (and to a lesser extent, on trade and foreign policy). When the Bush administration attempted to advance reforms during its second term, conservatives mobilized in opposition, killing attempt after attempt.

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The Republican base remained adamantly opposed to reform four years later. It was Rick Perry's call for compassion, not his debate flub, that sunk his 2012 candidacy. To win the nomination, Mitt Romney ran on a platform of self-deportation. He won just 27 percent of the Latino vote, 13 points less than Bush in 2004, and his loss left party leaders scrambling for renewed efforts at immigration reform. And thus the Republican autopsy and the Gang of Eight, the effort at reform that crippled Marco Rubio's candidacy.

In light of these tensions, it's no wonder that Donald Trump, with his cries of rape and murder and his pledge to build a wall and make Mexico pay for it, would catch fire with the same base that had again and again killed immigration reform. And over the past 15 months, as Donald Trump flipped and flopped on everything else, he kept true to his wall. He described it in loving detail: the cement, the rebar, the 10 feet that it gained every time a Mexican politician scoffed at his nonsensical proposal.

It is, in fact, the physicality of Trump's wall that's making the attempt to jettison it so difficult. Trump surrogates have been talking about the "virtual" wall, a digital rather than physical barrier at the border. But Trump wasn't promising to make his wall 10 megabytes higher. His "10-foot" additions weren't hinting at binary code. By wobbling on both his wall and mass deportation, the pillars of his immigration policy and thus his campaign, Trump has made clear he's just another shell game operator.

Every good con artist has a shill, and Trump is no exception. On Monday, Rush Limbaugh copped to having been in on the con from the start. A caller railed against Limbaugh for giving Trump a pass on his immigration reversal. "I guess the thing is ... I never took him seriously on this," Limbaugh shrugged. And then he went one step further. He admitted, as he does from time to time, that he's in it for the ratings and the money. "I am a radio guy. I do a radio program. And my success here is defined by radio and broadcast business metrics, not political."

Actually, Limbaugh's explanation could be Trump's as well. He also measures success by broadcast business metrics, not political ones, which is why he gets confused when he does well in the TV ratings but not in the polls. At heart both men are entertainers looking to maximize their audience and profits, ready to cash in on people's frustrations with the political system that has let them down.