When my grandfather's grandparents arrived on the shores of Jersey City, having fled famine in Ireland, the city was joined in an epic battle waged against the immigrants by a nativist party nicknamed the Know-Nothings.

The Irish were not to be trusted, the Know-Nothings said, especially because of their strange religion-Roman Catholicism. Cast as an army of infiltration sent into America by the pope, the Irish were, for a time, barred from employment in the police force and other government offices through the connivance of Know-Nothing state legislators, who conferred a new charter on the city, which was later struck down by the New Jersey Supreme Court.

It's difficult to imagine today the discrimination faced by the starving Irish at the time of their mass migration to the U.S. Catholicism is now the largest Christian denomination in the country, and Irish Catholics are well represented at the highest levels of society. Somewhere along the way, the Irish became regular white people-so regular, in fact, that I'm guessing we're amply represented among the supporters of Donald Trump's candidacy for the 2016 Republican presidential nomination.

I make that assertion looking not only at the polls that gauge the standing of the GOP hopefuls in relation to one another, but also at the general-election polls that match up the various contenders in one party against Hillary Clinton, the likely Democratic nominee. In those polls, Trump and Clinton are running about even. While not predictive a year before the next presidential election, they are a measure of public sentiment.

And right now, it looks like nearly half the public is ready to believe any hate-spawned lie that comes out of Donald Trump's mouth. That's a lot of hate-and some mighty big lies.

Like the one about Jersey City, for example. After the November 13 terrorist attacks in Paris, Trump saw an opportunity to expand his anti-Muslim, anti-immigrant franchise by uttering this whopper: that on September 11, 2001, the streets of Jersey City were filled with "thousands and thousands" of (presumably Muslim) people celebrating the fall of the World Trade Center towers, which loomed over Jersey City, sometimes called "Wall Street West."

There were no such street celebrations that dreadful day; Trump has not been able to produce one frame of the television footage of the festivities he claims were broadcast. The best he's been able to come up with is a Washington Post article that reported unsubstantiated rumors of rooftop parties-allegations long since debunked.

But save your efforts, professional fact-checkers. Your Pants-On-Fire rating of Trump's claim, which is pretty much an incitement to violence, will fall on deaf ears, for it simply confirms the worldview of too many Americans. Never mind that the worldview is based on fear and prejudice and ethnic chauvinism; America has a long tradition of indulging that ugly strain. Just ask a Japanese American, or an African American-or even an Irish American who actually knows some history of her people.

Trump hardly contains his hatred for the mosques he promises to monitor once he's president and the police state he plans to expand is in place. Anybody who's not white is ripe for vilification, be they Latin American, Asian, or black.

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On November 22, Trump tweeted a graphic making the rounds in white supremacist circles that is filled with false crime statistics concocted to impugn African Americans.

(Just the day before, several of his supporters beat a black civil-rights activist at an Alabama Trump rally.) The graphic listed the rate of white homicide victims killed by blacks as 81 percent, when the FBI crime states show that, actually, 82 percent of white homicide victims are killed by white people.

The next day, a small group of white men shot five Black Lives Matter protesters in Minneapolis outside the 4th Precinct police station, where the protesters have camped out to protest the November 15 police killing of Jamar Clark, who was unarmed and, according to witnesses, in handcuffs.

Of course, one can't draw a causal connect between the tweeted Trump lies and the shooting of black people protesting police killings; one wouldn't dare.

Yet, taken together, they reveal the treachery of the American political landscape in these days of fear and hate. When Trump first uttered his Jersey City lie, Ben Carson, his closest rival for the nomination, said he had seen the same footage that Trump fantasized. (He's since walked that back.) And what of New Jersey's governor, also vying for the GOP nomination?

"I do not remember that, and so it's not something that was part of my recollection," Chris Christie told reporters on Sunday at a campaign stop in New Hampshire. "I think if it had happened, I would remember it, but, you know, there could be things I forget, too."

Wouldn't want to piss off all of those big-hearted voters leaning toward the Donald now, wouldja?

Republicans often use the cover of calling their party the Party of Lincoln, as if it were they themselves who emancipated the enslaved Americans of African descent in 1863.

But Abraham Lincoln himself offers an apt description of today's GOP, in this 1855 letter to his friend Joshua Speed, in which he waxes on the Know-Nothings:

Our progress in degeneracy appears to me to be pretty rapid. As a nation, we begin by declaring that 'all men are created equal.' We now practically read it 'all men are created equal, except negroes.' When the Know-Nothings get control, it will read 'all men are created equal, except negroes, and foreigners, and catholics.' When it comes to this I should prefer emigrating to some country where they make no pretence of loving liberty-to Russia, for instance, where despotism can be taken pure, and without the base alloy of hypocracy [sic].

There's a toxic fluid in the bloodstream of the American body politic. Trump exemplifies it, but it doesn't begin and end with him.

Until we're willing to explore why, when given the choice between the hatemonger and Hillary Clinton, some 44 percent of the U.S. electorate think a President Trump would be a pretty good idea, "our progress to degeneracy," to borrow Lincoln's term, throttles into overdrive.