As is her job, Ann Coulter set the Internet on fire on Monday night, tweeting out this racist dog-whistle about the election:

While it's hard to tell if the tweet was serious or just as another attention-seeking troll, the responses to it were full of factual rebuttals.

For one thing, Coulter's restrictions would have prevented her Donald J. Trump from voting for himself, as the Republican candidate had a mother from Scotland and grandparents from Germany. It also would leave out his wife Melania, born in Slovenia, as well as his daughter Ivanka, whose mother is the Czech-born Ivana. Also ineligible to vote would be Trump's vice presidential candidiate, Mike Pence, whose grandfather was born in Ireland.

Beyond that, Coulter's tweet, either intentionally or accidentally, is strikingly reminiscent of Nazi-era racial purity laws, which stipulated that anyone with less than three German-born grandparents were liable to be denied citizenship, and possibly end up in prison or worse.

It also displays a profound lack of knowledge about the parentage of U.S. presidents. Under Coulter's rules, nine of the first ten heads of state wouldn't even be considered Americans, as they were all born under British rule. Thomas Jefferson's mother was also born in England, while both of Andrew Jackson's came from Northern Ireland. James Buchanan, Chester Arthur, Woodrow Wilson, and Herbert Hoover all had foreign-born parents. Even conservative lodestar Ronald Reagan would have been disqualified under Coulter's proposal, as his maternal grandmother was born in England.

Ted Cruz and Marco Rubio would also be out, both with Cuban-born parents. Who would be eligible to vote, according to Coulter? Millions of African-Americans who can trace their ancestry back to slaves kidnapped during the 18th and 19th centuries.

Even if just a desperate ploy for attention, Coulter's tweet falls in line with her long record of racist outbursts — and is a sober reminder of the kind of anti-immigrant sentiment that's fueled Trump campaign.