Donald Trump has been taunting fellow GOP contender Jeb Bush for a while about his immigration plan, recently going so far as to call it “baby stuff.”  After weeks of keeping his head down, Bush is finally hitting back, slamming Trump’s $500 billion dollar plan for border security as unrealistic and a waste of taxpayer money:

I’m not going to get into the issues of what he said and I said.  The simple fact is that his proposal is unrealistic.  It will cost hundreds of billions of dollars, it will violate people’s civil liberties, it will create friction with our third largest trading partner that is not necessary, and I think he’s wrong about this.

Bush also took the opportunity to suggest Trump get better educated on border issues:

If he’s interested in a more comprehensive approach he might want to read my book, “Immigration Wars,” which I published four years ago.  I welcome Mr. Trump into the debate.  I think that’s great.  He’s a serious candidate, and he ought to be held what serious candidates need to be held to.  He needs to be held to account for his views.

The New York Times suggests that this is a part of Bush’s new playbook for dealing with Trump: “Hit back, with force and creativity, over and over again in the coming weeks.”  So far, Trump isn’t impressed:

In a phone interview Monday, Mr. Trump laughed at the suggestion that he read Mr. Bush’s book on immigration. “That would be exciting,” he said dryly.

While the Republican field has started releasing immigration plans over the summer, it’s becoming clear that just having a plan isn’t enough.  If candidates want voters to give it serious consideration, they need to talk about it.  I expect we’ll hear a lot more from Bush and Trump about their visions for immigration reform in the future.

Nick Arnold is a researcher for American Principles in Action.