When Pat Buchanan was finally fired by MSNBC in February 2012, it probably symbolized the end of an era for our culture and, in retrospect, for the Republican Party. Buchanan was the first person Richard Nixon hired when he started his campaign for the presidency in the 1968 election. Buchanan grew up in segregated Washington DC, and he liked it that way. He was one of the first strategists to realize that the Republican Party could make a comeback from its post-1964 nadir by adopting a Southern Strategy based on racism. He’s the living embodiment of the persistence of a Jim Crow mentality in this country and within the modern Republican Party. He survived and prospered in the Washington media despite persistent accusations of anti-Semitism (which is usually fatal) because he carried the torch for that Jim Crow mentality. Buchanan could oppose the Republican party line on trade, on foreign policy, on Israel…but he could appear on cable television from morning until night because his positions on racial matters were mainstream conservative positions. No one lost their job for being anti-black.

Yet, what ultimately cost him his job wasn’t defending Nazi war criminals or minimizing the impact of the Holocaust. What cost him his job was the publication of his book Suicide of a Superpower: Will America Survive to 2025, which argued that whites had lamentably lost control of America. The following two passages from that book crossed some kind of invisible line that existed by late 2011, when he was initially suspended, but did not exist at any time prior to that.

“Those who believe the rise to power of an Obama rainbow coalition of peoples of color means the whites who helped to engineer it will steer it are deluding themselves. The whites may discover what it is like to ride in the back of the bus.”

“Mexico is moving north. Ethnically, linguistically, and culturally, the verdict of 1848 is being overturned. Will this Mexican nation within a nation advance the goals of the Constitution—to ‘insure domestic tranquility’ and ‘make us a more perfect union’? Or has our passivity in the face of this invasion imperiled our union?”

Buchanan was an ubiquitous presence on cable television from its inception, but he is now gone. Disappeared. Socially unacceptable. He says he’s been blacklisted, which is an ironic term under the circumstances. Yet, he can still write, and he is freer than ever to be candid about his views. What cost the Republicans the 2012 election? Buchanan has an opinion.

First, he defines how the modern GOP found its initial success:

In 1966, Nixon led the GOP back to a stunning victory, picking up 47 House seats. In 1968, he united the Rockefeller and Reagan wings and held off an October surge by Hubert Humphrey, which cut a 13-point Nixon lead to less than a point in four weeks.

In 1972, Nixon swept 49 states. The New Majority was born. How did he do it?

Nixon sliced off from FDR’s New Deal coalition Northern Catholics and ethnics — Irish, Italians, Poles, East Europeans — and Southern Christian conservatives. Where FDR and Woodrow Wilson had won all 11 Southern States six times, Nixon swept them all in ’72. And where Nixon won only 22 percent of the Catholic vote against JFK, he won 55 percent against George McGovern in 1972.

Then he describes how they undermined themselves.

What killed the New Majority?

First, there was mass immigration, which brought in 40 to 50 million people, legal and illegal, poor and working class, and almost all from the Third World. The GOP agreed to the importation of a vast new constituency that is now kicking the GOP into an early grave.

When some implored the party in 1992 to secure the border and declare a “timeout” on legal immigration to assimilate the millions already here, the party establishment repudiated any such ideas.

“We are a nation of immigrants!” it huffed. Well, we sure are now.

Buchanan is probably correct that the changing demographics of the country have finally tipped the country permanently away from unreconstructed Jim Crowism-by-another-name. If we had a rematch today between Richard Nixon and George McGovern, McGovern would win more than one state. He might even win the Electoral College and the presidency.

The firing of Pat Buchanan was a canary in a coal mine that ought to have warned the Republican Party that Romney’s strategy was not going to work. The country had finally become diverse enough that racial polarization was no longer a winning strategy.

Some people are surprised that the Republicans took their defeat so hard. I mean, it never looked for a single moment like Obama might actually be defeated. We talk about how the Republicans deluded themselves with talk about skewed polls, but the real trauma is the realization that Pat Buchanan’s brand of racial politics no longer works.

Without race resentment, the conservative movement has precious little to talk about. People are bored of talking about the debt. In a post-Bush era, Republicans are divided on foreign policy and defense. The old social wedge issues now cut against the GOP.

The Republicans have begun a period of reflection. It started the moment that Mitt Romney conceded defeat, but it could have started the day that Pat Buchanan was finally deemed too racist to be a respectable mouthpiece for the party on cable television.