John Danforth, a long-serving former Republican senator from Missouri, on Thursday became the latest unelected member of his party to condemn Donald Trump. In an opinion piece published in the Washington Post, Danforth ripped into Trump as un-American for sowing dissent and division. He correctly noted that “Trump is always eager to tell people that they don’t belong here, whether it’s Mexicans, Muslims, transgender people or another group. His message is, ‘you are not one of us,’ the opposite of ‘e pluribus unum.’ And when he has the opportunity to unite Americans, to inspire us, to call out the most hateful among us, the KKK and the neo-Nazis, he refuses.”

It’s hard to argue with that. But Danforth goes further, contending that Trump is also un-Republican, invoking Lincoln to claim the mantle of inclusiveness as the overarching principle of Republicanism and imploring “my fellow Republicans” not to permit Trump “to redefine the Republican Party.”

Not so fast. While language like this will be comforting to Republicans looking to convince themselves they are not defined by their leader, it is dangerously in error. Trump did not emerge in a vacuum. He is the end product of decades of division employed for electoral advantage. You can draw a straight line from Nixon’s southern strategy to Reagan’s welfare queens and Bush’s Willie Horton ad to Birtherism to Donald Trump. To say, as Danforth does, that “our party has been corrupted by this hateful man” is to deflect from this history. And without a correct diagnosis it will be impossible for Republicans to treat the disease consuming their party.

You need look no further than the unwillingness of most elected Republicans to speak or act against Trump for evidence that the rot extends well below the top. Most Republicans who have to face real voters live in fear of Trump’s supporters. I have written in recent weeks about Republican Island, the small but politically critical mode of reactionary opinion that constitutes Trump’s base. Voters didn’t just suddenly appear on Republican Island. They were cultivated over many years, fed alternative facts and primed to embrace the man Danforth rightly calls “the most divisive president in our history.” Danforth is of course correct when he tells his fellow partisans that “we Republicans must disassociate ourselves from Trump by expressing our opposition to his divisive tactics,” but doing that requires acknowledging that those tactics do “represent what it means to be a Republican”—and have for many years.

Danforth is absolutely right when he says that the country needs a responsibly conservative party, but the Republican Party as it presently exists is neither responsible nor conservative. It is irresponsible and reactionary, and for this Donald Trump could not be a more suitable leader. Republicans could put an end to this tomorrow through readily available constitutional remedies. But they won’t—at least not yet. That most elected Republicans won’t even join Danforth in his call for vocal opposition to Trump is a measure of how irresponsible they are willing to be in the face of their reactionary voters.

The only way to save the Republican Party in any recognizable form is to start walking Republican voters back toward the traditional political right. Only Republican leaders can do this by dismantling the messaging and fundraising machinery that thrived on stoking division while leading the anti-Trump rebellion they have been avoiding for almost two years. This would require an enormous sacrifice of power and influence and the recognition that it will take a long time for the party to return to competitiveness. Virtually no Republican electeds are willing to go there yet. But it should be extremely clear that the alternative is an emboldened Donald Trump consuming the Republican Party and irreversibly accelerating Republican decline. One would hope that as this becomes apparent the time for denial will end and Republicans will begin to admit that Trump’s divisiveness is not redefining the party as much as taking a once-successful strategy of racial, economic and social division to its naturally destructive conclusion.