Republicans made gay marriage a wedge issue. Now that it hurts them, they call it “divisive.”

It’s hard to believe these are the same guys who were whooping it up about gay marriage in 2004. What happened?

To answer that question, look at the polls. In 1996, when Republicans campaigned successfully for a federal law against gay marriage, most Democrats opposed the legality of same-sex marriages. They rejected the idea by approximately 60 to 33 percent in Pew and Gallup surveys. Independents closely matched that split. Republicans opposed gay marriage even more strongly, by about 80 to 15 percent in both polls.

In 2004, Republicans were still firmly set against gay marriage. Their margin of opposition was 80 to 19 in Gallup’s May survey, 78 to 17 in Pew’s combined annual data, and 73 to 24 in a February Washington Post/ABC News sample. The margin of opposition among independents, however, had declined considerably. It was 53 to 37 in Pew’s data, 52 to 44 in the Gallup poll, and 48 to 44 in the Post survey. Democrats, meanwhile, were now roughly split. In February, the Post found them evenly divided, 48 to 47 percent. A later Post survey, taken in August, found them opposed by 52 to 43 percent. Pew’s yearly average showed them opposed by 50 to 40 percent, while Gallup’s May sample had them favoring gay marriage by 51 to 46 percent.

Since then, public opinion has continued to shift toward accepting gay marriage. Democrats now support it by margins of 64 to 32 in the Post’s March 2012 survey, 65 to 34 in Gallup’s May sample, and 59 to 31 in Pew’s combined 2012 data. Independents in all three polls now favor gay marriage: 54 to 42 according to the Post, 52 to 38 according to Pew, and 57 to 40 according to Gallup. At the same time, the Republican margin of opposition has fallen. It’s 74 to 22 as measured by Gallup, 68 to 23 as measured by Pew, and 57 to 39 as measured by the Post.

Republicans aren’t split as deeply as Democrats were in 2004. Nor are Democrats as united today as Republicans were back then. And if you look at polling data over time, you’ll see that public opinion has lurched or backtracked along the way. Just last night, CBS and the New York Times released a sample that leans further to the right.

But overall, the trend is clear. Democrats, who initially opposed gay marriage and then were evenly divided, are gradually uniting in favor of the idea. Republicans, who used to be united against gay marriage, are becoming more closely divided. And independents, who used to lean against gay marriage, now lean toward it. In 2004, if you raised gay marriage as a wedge issue, you divided Democrats, united Republicans, and pushed most independents to the right. Today, if you raise gay marriage as a wedge issue, you divide Republicans, unite Democrats, and push most independents to the left.

That’s why Romney and other Republicans who loved to talk about gay marriage in 2004 now call Democrats divisive for bringing it up. Republicans are happy to divide the country. But they no longer like the way this issue cuts.

William Saletan's latest short takes on the news, via Twitter: