Last Thursday, the day after President Obama
finally endorsed gay marriage, his campaign released a
video that
faults his presumptive Republican opponent, Mitt Romney, for not
doing likewise. “President Obama is moving us forward,” the ad
says. “Mitt Romney would take us back.”

In a sense, Obama is the one going back, returning to a
position he took as a political novice in 1996. But the same
changes in public opinion that made it thinkable for him to stop
equivocating on gay marriage present a challenge to Romney as he
repositions himself for the general election.

Sixteen years ago, when Obama supported “legalizing same-sex
marriages” as a candidate for the Illinois Senate, a
Gallup poll found that only 27 percent of Americans agreed with
him. According to a Gallup poll conducted this month, that number
has risen to 50 percent.

A new CBS News
poll indicates that support for legal recognition of gay
couples (not necessarily “marriage”) is even higher. Thirty-eight
percent of respondents said “gay couples should be allowed to
marry,” while another 24 percent said they should be “allowed to
form civil unions.” Only 33 percent favored “no legal recognition.”
Surveys during the last few years have yielded similar results.

In short, “no legal recognition” for gay couples clearly has
become a minority position, which poses a problem for Romney. The
former Massachusetts governor has opposed
same-sex marriage since the beginning of his political career, and
he
favors a constitutional amendment that “defines marriage as a
relationship between a man and woman.”

The Obama campaign’s video implies that Romney—unlike Obama’s
Republican predecessor, George W. Bush—also opposes civil unions,
but that is not true. Since running for governor in 2002, Romney
has said
he supports “domestic partnerships” for same-sex couples that
include “the potential for health benefits and rights of
survivorship.” What else they might include is not entirely clear,
and this is the tricky part for a candidate trying to keep social
conservatives happy without alienating swing voters by seeming
intolerant or insensitive to the problems gay couples face because
of their unequal legal treatment.

Romney’s idea of domestic partnerships clearly does not go as
far as the civil unions that Obama favored until last week (which
he
said would provide “all the rights” of marriage). “I do not
favor marriage between people of the same gender,” Romney
said after Obama’s announcement, “and I don’t favor civil
unions if they’re identical to marriage other than by name.”

But contrary to the Obama campaign’s video, Romney does support
shared health plans as well as joint adoption. “If two people of
the same gender want to live together, want to have a loving
relationship and even want to adopt a child,” he
said on Fox News last week, “in my view that’s something that
people have the right to do.”

Already this is dangerous territory as far as social
conservatives are concerned, which explains why Romney’s campaign
later insisted he was only explaining what Massachusetts and many
other states allow. “He thinks a traditional family is far better
for children,” a spokeswoman
told CNN, but “he acknowledges it’s a state issue” and “did
nothing to change it” as governor of Massachusetts.

As that whipsawing statement suggests, federalism will get
Romney only so far, especially since he has chosen to nationalize
the issue by calling for a constitutional ban on gay marriage. If
the ban does not apply to civil unions, it will not stop states
from allowing legal arrangements “identical to marriage” but for
the name, which Romney
says he opposes. But if the federal government tries to prevent
those, states won’t really be free to “make decisions with regard
to domestic partnership benefits,” the approach he says he
favors.

Romney is not the only Republican with conflicting impulses on
gay marriage. In the CBS News
survey, 70 percent of Republicans supported a constitutional
ban, while 63 percent said the issue should be left to the
states.

Jacob Sullum is
a senior editor at Reason and a nationally
syndicated columnist. Follow him on Twitter.