In a Time magazine column the other day, Joe Klein scolded the Democrats for being overly preoccupied with identity politics. In its admirable drive to be inclusive, he argued, the party has treated its constituents not as a population united by common ideals and interests, but as an array of caucuses to be pandered to: African-Americans, gays, Latinos, women, youth and so on. Klein wrote that “if I’m a plain old white insurance salesman, I look at the Democratic Party and say, What’s in it for me?”

The Republicans have exactly the opposite problem: they seem to be going out of their way to make their party inhospitable to everyone but that plain old white insurance salesman. They have alienated the majority of women and the vast majority of blacks. The fraction of young voters who call themselves Republican has been shrinking for 20 years, to about one in three. The Republicans are repelling the surging Latino electorate by making themselves the party of police checks, higher fences, English-only-spoken-here and self-deportation.

And that insurance salesman had better not be gay. The Republicans have enshrined the status of homosexuals as second-class citizens in the party platform. At their convention in Tampa, the Republicans attempted a show of ethnic and gender diversity. But as my colleague Frank Bruni pointed out, gays and lesbians were denied even that token pageantry.

Which brings me back to a story I’ve been following closely over the past year.

In June of 2011 the state of New York got in step with the slow march of history, legalizing same-sex marriage. Urged on by Gov. Andrew Cuomo, all of the State Senate’s Democrats voted in favor except a lone fire-and-brimstone minister from the Bronx. The Republican Party opposed the measure, but four G.O.P. senators broke with their party to provide the margin of victory: Stephen Saland, Roy McDonald, Mark Grisanti and Jim Alesi.