More than any other issue, Donald Trump’s stance on immigration will have the biggest impact on post-2016 national politics. His opposition to immigration is his signature and most consistent opinion during the entire campaign. Trump’s rise was fueled by nativism — from his early statements on Mexican rapists to his first position paper to his current campaign. Similarly, his likely defeat in November will be due to the limited electoral appeal of Know-Nothingism — opening the way for more liberal immigration laws.

Trump’s nativism and his way of expressing it powered his rise. The anti-immigration opinion of Republican primary voters was the best predictor of their individual support for Trump. Ann Coulter said, “Americans have been begging their own party to shut it down, to stop this endless immigration for decades.” Even the anti-Trump editors of the National Review wrote that “His signature issue is concern over immigration … He has exploited the yawning gap between elite opinion in both parties and the public on the issue.”

While the Republican Party has become increasingly anti-immigration, public opinion has swung the other way. A 2016 Gallup poll found that 38 percent of Americans want to decrease immigration — a 27 point decline from its peak in 1993. Meanwhile those who are happy with the current levels or support an increase are up by the same amount. Tellingly, the percentage of those who want more legal immigration has more than tripled to 21 percent. An increasing Republican share of a shrinking anti-immigration opinion will not serve the GOP well.

Immigration restrictionists who blamed Trump’s rise on politicians who ignored the voters on this issue have locked themselves into a bind. It’s true that Trump’s rise can be credited to his anti-immigration position. But that also means that his drop in the polls and likely loss in November will also be blamed on his nativism.

Some people will try to deflect a loss by blaming Trump’s style rather than his substance. Mark Krikorian, executive director of the anti-immigration Center for Immigration Studies, said he’s glad Trump “aired these issues” but that “it would be nice if we had a different messenger.” National Review editor Rich Lowry implored Republicans to pander to Trump on immigration without his bombastic rhetoric. Both misunderstand populist movements and their frequent anti-immigration roots.

Successful nativist populists cannot be soft spoken and polite. Rick Santorum, Mike Huckabee and Scott Walker all had similar immigration positions to Trump’s yet they lost because they lacked his boorish personality and vulgarity. For nativism to advance, it must appeal to nativists and they do not want to hear soft-spoken, measured and articulate arguments for limiting immigration. They want Trump-speak: crude name-calling and a projection of toughness. It’s impossible to separate Trump’s substance from his style and win a GOP primary.

Trump is destroying the intellectual respectability of immigration restrictionism. It’s not fair, but from now on the smarter, politer and better spoken critics of immigration will be lumped in with Trumpism and its probable electoral defeat. Hillary Clinton and the Democrats are ascendant, buoyed by their relative support for immigration and Trump’s position on it, thus reinforcing the pro-immigration opinion trend among Democrats and independents. Republicans scarred by this election will work double to avoid more Trumps in the future.

Remarkably, the GOP has been here before. California turned blue in the mid-1990s because the Republican Party pitted themselves against immigrants and, in the court of public opinion, Hispanics. That won the GOP an election in 1994 and lost them virtually every one since (Schwarzenegger was a fluke). Trump’s Republican Party is repeating this mistake on a national level — just like the Federalist and Whig parties did shortly before their downfalls.

Instead of copying the playbook of the nearly extinct California GOP and other failed political parties, the Republican Party and its voters should copy Texas. Hispanics are 38.6 percent of the populations in both states but the politics are worlds apart. That’s because Texas Republicans like George W. Bush and Rick Perry ignored the California model and realized that demographic are not political destiny. By courting immigrants and publicly refusing nativism they made Texas even more conservative.

Donald Trump will almost certainly lose this election, taking down Know-Nothingism and any intellectual respectability it may have left. This will not just be an opportunity for the Democrats but also one for conservatives who want to embrace America’s proud history of welcoming immigrants and assimilating them. Trump’s likely defeat should convince conservatives and Republicans that instead of standing athwart immigration yelling “stop,” they need to start saying “welcome” and really mean it.