If you'd asked several months ago what message Democrats would adopt at their convention, I probably would have predicted a portrayal of all Republicans as responsible for Donald Trump's sins.
That is, Democrats would claim that all Republicans, up and down the ballot, were tainted with Trumpism, and that all of them would have to answer for their standard-bearer's foibles and fear-mongering.
The message would go something like this: For Trump's mockery of a disabled reporter; for his arguments that a federal judge can't do his job because of his Mexican descent; for his calls for an unconstitutional religious test to be applied to immigrants; and for his disparagement of women, minorities and war heroes, all Republicans ought to be held accountable and thrown out of office.
This prediction would have been wrong.
Rather than demonizing the entire GOP, Democrats have lately portrayed Trump as distinct from other Republicans, as not a "real" Republican or a "true" conservative. In so doing, Democrats have absolved Republican politicians of responsibility for his excesses -- and Republican voters of any obligation to elect him.
Many have noted that the Democratic convention last week liberally co-opted traditional Republican iconography. American flags abounded; Democrats name-checked family values, faith, patriotism and the military, all topics traditionally more closely associated with Republicans. Convention organizers recruited Republican speakers to endorse Hillary Clinton.
But Democrats not only paid homage to Republican tropes and leaders. They also expressed great deference to the Republican Party itself, elevating the GOP to idealized heights. In contrast with previous party confabs, this Democratic convention presented Republicans not as enemies to be vanquished but respected rivals undeserving of Trumpian turpitude.
The message for those watching at home: Trump is a pretender to the conservative throne.
"He's taken the Republican Party a long way, from 'Morning in America' to 'Midnight in America,'" Clinton declared in her Thursday night speech, in an unsubtle allusion to the GOP's patron saint, Ronald Reagan.
"What we heard in Cleveland last week wasn't particularly Republican -- and it sure wasn't conservative," President Obama argued the day before.
"A man who embraces the tactics of our enemies, torture, religious intolerance. You all know, all the Republicans know, that's not who we are," added Vice President Biden, perhaps giving Republicans too much credit.
Such arguments were a clear appeal to crossover voters. If Trump isn't a "real" Republican, well, then self-identified Republicans shouldn't feel disloyal if they vote against him.
In other words: Welcome, white college graduates! Welcome, suburban married women! Welcome, Rockefeller Republicans! We're not asking you to completely ditch your partisan tribalism; we're just suggesting you redirect it.
Or as Democratic vice-presidential nominee Tim Kaine put it even more explicitly during his convention speech: "If any of you are looking for that party of Lincoln, we've got a home for you right here in the Democratic Party."
At least for one election.
If some of this Trump-is-not-a-true-conservative rhetoric sounds familiar, it's because we also heard it a few months ago -- but from Republicans, during their presidential primary. Jeb Bush and Marco Rubio in particular railed against Trump's ideological impurities.
This line of attack was not exactly successful in turning the primary base away from Trump. Whether it now works on more moderate Republicans, during the general election, remains to be seen.
What we do know is that this strategic distinction that Democratic leaders are drawing -- between the truly principled conservatives and one truly unprincipled interloper -- lets too many Republicans off the hook.
Republican leadership has been laying the groundwork for Trumpism for years, after all. They did it when they questioned Obama's legitimacy as a natural-born citizen, as a Christian and as a democratically elected president empowered to appoint federal judges. They did it when they used coded language about "welfare queens" and "states' rights" and "religious freedom" and "illegals." Trump may have taken their dog whistles down a few octaves, so that they're now audible to regular humans, but he owes the original melody to earlier, allegedly "truer" Republicans.
Even today, large majorities of self-identified Republican voters support the most repugnant aspects of Trumpism, such as his proposed ban on Muslim immigrants and his call for Russia to hack Clinton's emails. And even today, their supposedly principled, more moderate Republican leaders -- such as Paul Ryan and Mitch McConnell -- can't muster the nerve to un-endorse the man who peddles this garbage.
Republican leaders often demand that moderate Muslims loudly repudiate the more radical members of their faith, the extremist fringes that support violence and oppression. Democrats should hold Republicans to the same standard.
Catherine Rampell's email address is firstname.lastname@example.org. Follow her on Twitter, @crampell.