According to some polls, Donald Trump has been pulling as little as 0 percent of the black vote in key battleground states such as Ohio and Pennsylvania. Zero percent! That's mind-boggling and sure, it might pick up after his recent speeches identifying with the plight of African Americans living in urban areas that have been under Democratic control for decades.

But if we're being honest, it's not going to change very much. That's not all Trump's fault, either. It represents a decades-long trend that has seen Republicans essentially abandon all hopes of cracking the lowest possible double digits among black voters. In 2012, Mitt Romney got just 6 percent of black votes. (One Republican who has done better is Ohio Gov. John Kasich, who earned 26 percent of the black vote in his 2014 re-election race).

It wasn't always this way, of course, and looking at how Republicans went from being the default party of black voters after the Civil War to being a pariah among them is a way of understanding one highly probable future for the GOP as a minor party that represents a smaller and smaller bloc of voters who identify as "white" and "American" in strictly nativist terms.

The GOP's declining appeal to black voters—again, approaching zero in the Year of the Donald!—is paralleled by the party's declining appeal to Hispanic voters, too. According to the Census, blacks currently make up about 13 percent of the population while Hispanics account for about 18 percent. In an August 11 Fox News Latino poll, only 20 percent of Latinos support him, lower even than Mitt Romney's dismal 27 percent showing among Latinos in 2012, which was itself lower than John McCain's 31 percent in 2008. Between blacks and Latinos, then, the Republican Party is effectively writing off almost 31 percent of the vote before the first ballot is cast in November. And given broad demographic trends, things can only get worse for the GOP.

What's going on here and what it does it say about Republicans and electoral politics in the 21st century? And what does it say about the possibility for a third party such as the Libertarians to drive up their own national numbers? The short answers: Absent a different agenda and outreach to groups they alternately demonize and ignore, the GOP will harden into an awful party of racial and ethnic resentment. For the LP, which embraces tolerance, diversity, and economic mixing and progress, the sky's the limit, especially if the Democrats continue to take minorities for granted.

As recently as 1960, the Republican Richard Nixon managed to get about 30 percent of the black vote. From the Civil War on, blacks had favored the "party of Lincoln" for self-evident reasons. Southern Democrats were segregationists and they worked hard not just at disenfranchising blacks at election time but in every way possible. Blacks weren't even allowed to attend Democratic national conventions until 1924. While he was no great friend to African Americans, Franklin Roosevelt began to win a majority of their votes in the 1930s, mostly for the same reasons he won a majority of nearly every group's votes during his four presidential campaigns. Blacks were more likely to be poor than average and they warmed to various FDR programs aimed at ameliorating poverty. Harry Truman, writes Brooks Jackson, won 77 percent of the black vote in 1948, the first year that a majority of blacks identified as Democrats (among other things, Truman integrated the armed forces and took civil rights more seriously than most of his predecessors).

While Eisenhower in '56 and Nixon in '60 did relatively well with black voters, Barry Goldwater's refusal to vote for the Civil Rights Act of 1964—and his willingness to run a campaign that tolerated (if it didn't actively court) segregationists—effectively ended the Republican Party's relationship with blacks. As former segregationists such as Strom Thurmond crossed the aisle to join the Republicans, the transition was complete and for the past 40-plus years, Republican presidential candidates have struggled to crack double digits with black voters. Running as the "law and order" candidate in 1968 and targeting urban violence (by war demonstrators and race rioters alike), Nixon no longer had much appeal for black voters. The last GOP candidate to crack double digits was George W. Bush in 2004, when he pulled 11 percent.

Something similar is happening with Latino voters, although the trend line is less uni-directional. In 2004, George W. Bush won 40 percent of the Latino vote (some reports put it a few points higher), but since then it has declined precipitously, down to Trump's pre-election share of 20 percent. The typical conservative Republican response to this is to invoke a master plan by Democrats and/or moral and ideological failings of Latinos. A few years back, I debated Ann Coulter at an event hosted by the great Independence Institute of Colorado. Among the topics was immigration. Coulter, who has taken credit for Donald Trump's pro-deportation stance in this election, claimed that Ted Kennedy was behind the push to bring in millions of Mexicans and other unmeltable ethnics from Africa, Asia, and especially Latin America, all of whom would inevitably vote for Democrats. "I don't think any time in the history of the world has a country changed its ethnic composition overnight like that," said Coulter, following a line of thought that is popular among many conservatives, right-wingers, and Republicans. "It was done by design. It was done to help the Democrats, and it did help the Democrats."

In fact, the immigration reform enacted in the mid-1960s, much in the spirit of Civil Rights legislation. Its chief authors were New York Rep. Emanuel Celler and Michigan Sen. Philip Hart, and its explicit goal was partly to route around the patently racist quotas from the 1920s that had been based on "national origins." Disturbed by the rise in immigrants from central and southern Europe, unapologetically racist lawmakers in the '20s laws moved to limit the number of Jews, Italians, Poles, Slavs, Irish, and other undesirable Europeans. New limits were pegged to percentages of the 1890 Census, when there were fewer foreigners from "bad" countries in the United States. The '60s reforms, on the other hand, were specifically designed to let Americans of European descent bring over parents and grandparents who had been stranded in the old country first by the Depression and then by World War II. Even as it put family reunification front and center in deciding who could come here, it also allowed for high-skilled folks to emigrate. It was passed against a backdrop of lower and lower levels of foreign-born people in the United States. By 1970, just 4.7 percent of the country was foreign-born, down from a peak of almost 15 percent in 1910.

By the mid-'60s, though, relatively few Europeans were interested in coming to America. Some of them were trapped behind the Iron Curtain and had no easy way West. Throughout free European nations, things were relatively good for most people after a truly grim period that started with World War I. The immigrants that have come to America post-1965 are mostly from Mexico, Latin America, and Asia. In the late 1980s, Ronald Reagan pushed hard to create a pathway to legalization and citizenship for undocumented immigrants who were overwhelmingly of Latino heritage. So you might want blame (or thank) Reagan far more than Ted Kennedy for changing our "ethnic composition overnight."

But you can and should blame Republicans for failing to appeal to ethnically diverse Americans in the 21st century. Demograhics are not destiny in politics but ever since the mid-'60s, the GOP has done a masterful, if not always conscious, job of making sure that blacks and Latinos feel unwelcome.

In a great piece at Politico, Josh Zeitz writes that "unlike earlier waves, 90 percent of new Americans since 1965 hail from outside Europe—from countries like Mexico, Brazil, the Philippines, Korea, Cuba, Taiwan, India and the Dominican Republic." Where conservatives tend to see an undifferentiated blob of threats to American identity, Zeitz underscores that post-1965 immigrants "include evangelical Christians, traditional Catholics, anti-statist refugees and the kind of upwardly mobile, economic strivers whom the GOP courted assiduously in past decades."

Had the GOP worked to engage newer, non-European immigrants, the party wouldn't be in the position it's found itself in, where only rare presidential candidates such as Reagan and Bush II can appeal to one-third or more of a rapidly growing part of the citizenry. About the only time contemporary Republicans view immigrants as individuals is when they are signaling out the precise threat each different sub-group represents to the nation:

It's a party whose presidential nominee uniformly disparaged Mexicans as "rapists" and "killers" and called into question the impartiality of an American-born federal judge of Mexican ancestry. It's a party that casts a big enough tent to include congressional luminaries like Steve King (for every immigrant child "who's a valedictorian, there's another 100 out there who weigh 130 pounds and they've got calves the size of cantaloupes because they're hauling 75 pounds of marijuana across the desert"); Michelle Bachman (who claimed that a top aide to Hillary Clinton had family ties to the Muslim Brotherhood); Peter King (who contends that "80 percent, 85 percent of the mosques in this country are controlled by Islamic fundamentalists"); Louie Gohmert (the GOP's in-House intellectual, who raised concerns that Muslim immigrants might give birth to "terror babies" who "could be raised and coddled as future terrorists"); and Don Young (who apparently didn't receive the memo explaining that "wetback" is no longer a term used in polite company.)

"By 2050, non-Hispanic white Americans will comprise less than half of the U.S. population," writes Zeitz. "Had the GOP focused more on ideology and less on skin color, the party could have thrived from the immigrant influx."

But it didn't do that, any more than it has reached out to African Americans on a regular basis. There have been well-intentioned and sincere efforts by some Republicans (Jack Kemp comes to mind, and more recently Rand Paul), but the instinct among most conservatives and Republicans is to ignore issues in the African-American community or to reflexively side with the police, drug warriors, and others who are viewed negatively by blacks. When it comes to Latinos and non-European immigrants, the same distancing act dominates, along with calls to establish English as an official language and appeals to protect bankrupt entitlement programs from pilfering by illegal immigrants who are simultaneously supernaturally lazy and so hard-working they take all of our jobs.

There is very little reason to believe that the Republican Party will pursue any meaningful interaction with racial and ethnic minorites or economic refugees, even when, as Zeitz underscores, they might have strong ties built on common religious and entrepreneurial interests. The attitudes of so many of the GOP's presidential nominees and boosters in the press have been resolutely hostile to seeing Mexican and Latino immigration as anything other than a scourge upon the land. A few years back, Tea Party favorite Marco Rubio worked on comprehensive immigration refrom legislation until he was shouted down by his own party. By the time he announced for president, he was only interested in talking about cutting off the flow of newcomers. Toward the end of primary season, the Cuban-American Ted Cruz took to attacking Donald Trump as soft on immigration because the billionaire had a "door" in his much-discussed wall on the U.S.-Mexico border. National Review, arguably the flagship publication of the conservative right, has been calling for reductions in immigration from Latin America for decades now and attacked Trump for being insufficiently tough on the issue.

The Republicans' unwillingness to interact with a more ethnically and religiously diverse America can be the Libertarian Party's gain. Former New Mexico Gov. Gary Johnson and former Massachusetts Gov. William Weld are the only candidates that are effusively pro-immigration, pro-trade, and socially tolerant. Coming from a border state with a large Latino population, Johnson in particular is in a position to talk about the benefits of immigration and the issues faced by newcomers and their families as well as by longtime residents. His focus on the sharing economy, school choice, and rolling back federal regulations that hamper entrepreneurship also should play well with both blacks and Latinos.

But none of this is easily achieved. Gaining support among any constituency is the result of hard work and years of toiling side by side and shoulder to shoulder. The Republican Party—including Donald Trump in his recent outreach to African Americans—isn't wrong to say that racial and ethnic minorities aren't benefitting from Democratic Party policies at the local, state, and federal levels. Social Security retirement benefits ultimately screw over blacks, who have shorter lifespans; protecting union teachers from competition by charters and other forms of school choice hurts low-income minorities most of all; far from welcoming illegals from Latin America, the Obama administration has deported record numbers and split up tens of thousands of families; and on and on.

But simply rattling off such talking points isn't going to win new votes. That only comes from concerted actions that start at the neighborhood level and work out and up through levels of power and government policy. The political opportunity is there, but it remains to be seen who, if anyone, will take it.