Congratulations, America: Jeb Bush is running for president! Or rather, he’s moving actively in that direction. As he announced on Facebook this morning, over Thanksgiving he spent some time with his family, eating and watching football. “We also talked about the future of our nation. As a result of these conversations and thoughtful consideration of the kind of strong leadership I think America needs, I have decided to actively explore the possibility of running for President of the United States.”

Roll your eyes if you will about the prospect of yet another Bush presidency — as Jeet Heer pointed out this morning, “the last time the GOP won the White House without a Bush on the ticket was 1972. The last time without a Bush or Nixon: 1928.” But Jeb’s entry could actually have a profound effect on the 2016 Republican primaries, in healthy ways.

Bush will immediately be in the front rank of candidates, simply by virtue of his name and the support he has within elite Republican circles. That means that he’ll get lots of press attention, and other candidates will inevitably engage him in policy arguments. And there will be arguments. The best way to understand the effect Bush will have on the primaries is to contrast him with Mitt Romney, another politician’s son and establishment favorite.

When Romney ran, in 2008 but especially in 2012, he dealt with his history of moderate stances by sprinting to the right, to assure base Republicans that he’d be there for them. It was awkward and uncomfortable, and hurt him in the general election. (You may remember his comment about getting undocumented immigrants to “self-deport.”) In general, Romney’s move to the right had the effect of narrowing the policy discussion within the primaries. He could, for instance, have made a detailed argument for the efficacy of the health reform he passed in Massachusetts. But since it was closely associated with the Affordable Care Act, he decided (probably correctly, as a short-term strategic matter) to join in the chorus of Obamacare condemnation. That was his approach to most issues — just say the same thing all the other GOP candidates said, as emphatically as possible. The result was a debate about who hated Barack Obama the most, which was not exactly enlightening.

Jeb Bush will be an enthusiastic participant in the 2016 version of that debate on many issues — don’t fool yourself into thinking he isn’t a conservative — but on a couple of key issues, it will be all but impossible for him to move to the right. One of those is Common Core education standards. Someone like Bobby Jindal can change their stance on it, now that conservatives have decided that the standards are some kind of Stalinist brainwashing scheme — Jindal was once a Common Core supporter, but now hates it with every fiber of his being. But Bush can’t. The reason is that he isn’t just a supporter of Common Core, he’s probably its single more prominent advocate. He leads not one but two organizations (see here and here) devoted to promoting it.

Far more importantly, there’s immigration. Bush doesn’t just support comprehensive immigration reform, he talks about the subject in a very different way from most other Republicans. In a speech earlier this year, he described undocumented immigrants this way: “Yes, they broke the law, but it’s not a felony. It’s an act of love, it’s an act of commitment to your family.” And there’s no question that Bush feels this sincerely. He wrote a book on immigration reform (which his opponents’ aides are no doubt scouring for quotes that can be used against him). His wife is an immigrant from Mexico. He speaks Spanish. His kids look Hispanic. He’s not going to suddenly change his position on immigration.

What this means is that by being one of the top-tier candidates in the race, Bush instantly changes the immigration debate in the primaries. It isn’t that any of the other candidates are going to move to the left, but the discussion will not just be about who wants to build the highest border fence. There will be at least one person talking about immigrants in human terms.

It will be interesting to see how Bush approaches other issues on which his views are not as firmly held. For instance, for a variety of reasons, climate change could be a surprisingly prominent issue in the upcoming race. President Obama is already making some aggressive moves on climate — making an agreement with China to reduce emissions, having the EPA issue regulations limiting greenhouse gases — and when he does more, the GOP candidates will respond with predictable condemnations. As for Bush, he hasn’t said a lot on climate — at least once he called himself a climate “skeptic” and has expressed doubt both about whether climate change is occurring and what contributions humans have made to it, but some believe he’s pragmatic enough to actually take moves to combat it. Some Republican candidates are sure to plant themselves in the climate denial position; Bush could join them, or stake out a position more tethered to reality. Which he chooses will be revealing.

Jeb Bush faces some serious hurdles in winning the GOP nomination; a lot of primary voters are going to start by distrusting him, and it may not be possible to convince them otherwise. But his presence will make the race a little more complicated, and a little more interesting.