Sen. Heidi Heitkamp (LM Otero/AP)
Sen. Heidi Heitkamp (LM Otero/Associated Press)

If Sen. Ted Cruz (R-Tex.) is the bête noire of the Republican Party, Sen. Heidi Heitkamp (D-N.D.) has become that for her fellow Democrats. Former White House chief of staff William Daley felt so betrayed by Heitkamp’s vote last week against background checks for most gun sales that he demanded in a Post op-ed yesterday, “I want my money back.” But Daley and the Democrats should have seen it coming. For it was plainly apparent that Heitkamp was going to do the wrong thing on guns when she did the right thing on same-sex marriage.

The first sign of trouble was Heitkamp’s Sunday morning show debut on “This Week” on Jan. 6. When asked for her reaction to a Post story about the gun proposals under consideration by the White House, the freshman senator was blunt.

Well, I think you need to put everything on the table, but what I hear from the administration — and if the Washington Post is to be believed — that’s way — way in extreme of what I think is necessary or even should be talked about. And it’s not going to pass.

Heitkamp’s response shouldn’t have been too surprising. She has an A rating from the feared National Rifle Association. She hails from a red state that went for Republican presidential nominee Mitt Romney over President Obama by 20 points. And she won her seat by one percentage point. Still, her comments left many Democrats to wonder if Heitkamp was a Democrat in name only. So, when the parade of Democratic senators coming out for same-sex marriage got underway, Heitkamp must have seen it as a way to prove her Democratic bona fides to the national party.

After considerable pressure from activists and the media, Heitkamp said yes to marriage equality on April 5. But she was hardly courageous. Heitkamp was the fifth of six senators to do so that week and the 52nd senator overall to support same-sex marriage. More importantly, anti-gay groups no longer have a NRA equivalent to keep politicians in line. The arguments against civil rights for lesbians and gay men as espoused by the Family Research Council have lost their power. And groups such as the National Organization for Marriage have been discredited.

The country is also infinitely more accepting. The public opinion polls show a majority of the nation are in favor of marriage equality. Voters in three states legalized same-sex marriage in November. The GOP has been silent on the issue. And the arguments before the Supreme Court to uphold California’s gay-marriage ban and the so-called Defense of Marriage Act could only be described as token resistance to the rapid social change sweeping the nation.

Given all that, support for marriage equality is now the bare minimum required in the Democratic Party. As a result, it no longer has the ability to give pols a free pass on other issues, which explains the ferocity of Daley’s op-ed against Heitkamp. “It’s shameful when politicians put what they perceive is their own interest or that of some lobbying group ahead of what the great mass of the American people want,” Daley wrote. Heitkamp isn’t up for reelection until 2018. Plenty of time for her to prove Daley and other Democrats wrong.

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Jonathan Capehart is a member of the Post editorial board and writes about politics and social issues for the PostPartisan blog.