Who says you can’t turn the clock back?

Decades ago, near the end of the Age of Aquarius, a Republican congressman from Texas argued passionately that the federal government should pay for birth control for poor women.

“We need to take sensationalism out of this topic so that it can no longer be used by militants who have no real knowledge of the voluntary nature of the program but, rather, are using it as a political stepping stone,” said George H.W. Bush. “If family planning is anything, it is a public health matter.”

Title X, the law he sponsored that still funds family planning for the poor, passed the House by a vote of 298 to 32. It passed the Senate unanimously. A Republican president, Richard Nixon, enthusiastically signed it.

That was 1970.

This is now: The issue of birth control has suddenly become an obsession of the 2012 presidential campaign. To many observers, it seems that the clock has indeed been turned back.

Using birth control to have sex without making a baby has been settled social behavior, not a taboo but an ordinary prescription that virtually all American women present at the drugstore counter at some point in their lives. For many, it seems the common-sense way to avoid the prospect of abortion, which has been the really divisive issue of sexual politics.

Now gender warfare is erupting anew, at least in the spheres where political agitation thrives.

“Now you have a group of inflamed, enraged and constantly provoked women,” says Clare Coleman, who heads the National Family Planning and Reproductive Health Association.

Or, as Planned Parenthood’s president, Cecile Richards, said incredulously on Saturday during a rally in Austin:

“Somehow in this country, in 2012, this election might turn on whether women should have access to birth control.”

This might seem a bewildering turn of events, particularly when polls consistently show that (a) voters place jobs and the economy atop the list of their concerns and (b) large majorities of Americans of all faiths support the use of birth control, the most commonly prescribed drug for women between 18 and 44, and have done so for years.

But elections have a way of becoming national conversations — often unwieldy ones.

On the surface, this battle seems to have been joined by liberals and conservatives over President Obama’s insistence that all employers, including religious institutions, who provide health insurance include birth control at no cost.

This expansion of reproductive rights has thrilled liberals and dismayed conservatives, who see it as a violation of the separation of church and state enshrined in the Constitution.

Catholic bishops have been most opposed to the policy directive, because doctrine holds that any birth control except natural family planning is a sin against God. And the bishops have gained allies among those eager to overturn the entire health-care act. Repealing Obamacare, as Republicans call it, is a central pledge of all the men who want to be the Republican presidential nominee.

Layer on the public proclamations of one of those candidates, former senator Rick Santorum (Pa.), who has pulled ahead of the presumptive front-runner, Mitt Romney, in several national polls. He says that states should be free to ban birth control, that prenatal testing leads to abortion and that as president he would warn the nation about “the dangers of contraception.”

And the nostalgia of one his wealthiest backers for the days of abstinence when “gals” used to put Bayer aspirin “between their knees.” And the spectacle of House Republicans inviting an all-male panel to testify about the issue, which caused two congresswomen to stomp out of the chamber.

All of it made Sen. Patty Murray (D-Wash.) “feel like I woke up this morning on the set of ‘Mad Men,’ ” as she put it in a fundraising letter Friday, “and the Republicans have set their time machine for the 1950s.”

As is often the case in these matters, a variety of seemingly disparate issues get all tangled up — the Commerce Clause and Catholic doctrine, religious freedom and the right to privacy, feminism and liberty and conscience — at a time of economic uncertainty and vast demographic and societal transition.

Two states move to legalize gay marriage on two consecutive days; the Maryland governor pledges to sign the law, and his counterpart in New Jersey vetoes it. The Pew Research Center reports that interracial marriage is at a new high, and America learns of a new threshold crossed: More children are born to single women under 30 than to married ones.

These streams of social change from different sources tumble into one another and form a whirlpool that roils an already unsettled electorate.

Listen to Dianne Schram, who expresses a deeper sense of unease in a letter that appeared Saturday in the Detroit Free Press:

“It is a sad day in America when you have to compromise your religious rights. This disagreement has nothing to do with birth control, sterilization or abortion; it is the right given to us in the First Amendment, separation of church and state.

“Our freedoms of choice are slowly disappearing. The government is telling us what light bulbs to use, what kind of cars to drive, what to eat and what kind of health care is required.”

The long-settled right to contraception takes its place alongside all kinds of cultural struggles underway in America, over immigration, gay rights, lifestyle, government power and income inequality, at a time when people feel threatened and wary of giving away what they have.

Any one of those can erupt and spread in fast frenzy, amplified through the bullhorn of social media.

This latest argument sets “a claim of a certain good that should be provided” — free preventative care to all women — “versus a claim of freedom of association” — workers accept jobs with religious institutions knowing their beliefs might conflict with their own — says Patrick Deneen, a political science professor at Georgetown University and one of more than 100 scholars who signed an open letter that argues the administration’s “conscience” accommodation on the issue is unacceptable.

“This is a long-standing set of debates that go way back in American history implicating all kinds of issues — federalism, whether states should have certain kinds of organizations,” Deneen says. “It’s a very old issue that is popping up in an election year in surprising ways.”

Here’s another way to frame it, says Coleman, a Catholic with a long career in protecting and providing reproductive health care to the poor.

The church’s argument that providing birth control violates its conscience inevitably comes into conflict with the rights of its nonbeliever employees to have the same access to free birth control that others do. There are real-world concerns, too. Some say that if you want birth control, don’t work for a Catholic organization. Others say that an orderly or cafeteria worker in a large Catholic hospital might not have other job options or the money to buy her own birth control, which can cost up to $600 a year. Those who favor the new ruling add that these religious institutions also are receiving federal funds.

“That is the age-old question of where does your freedom end and where does your neighbor’s begin,” Coleman says, “and that is the core idea of America, and we are going to keep battling it out.”

The unresolved search for a “truly conservative Republican nominee and the backlash against Obama” has forged an election-year unity among Catholic bishops and religious evangelicals on an issue about which they usually disagree, says D.G. Hart, author of “From Billy Graham to Sarah Palin: Evangelicals and the Betrayal of American Conservatism.”

He says that the chief reason birth control has emerged as a prominent issue is because the religious freedom argument can be a fresh line of attack against Obama’s signature domestic accomplishment, which is being challenged in the courts.

“The way the American democratic system works is very peculiar,” says Hart, who teaches history at Hillsdale College in Michigan.

“But I don’t know that this [election cycle] is any worse than any other period when religious and racial preferences were expressed as cultural preference,” when a presidential election becomes an even more pointed referendum on what kind of society we want to construct.

He notes a disconnect among Republican voters between what the law currently requires and permits and “what people think Obama is requiring, and their perceptions go a long way to motivating them. You might think we would be better, and it is surprising that these cultural matters keep coming up this way. But that is where we are, and perhaps that is where we always will be. It is the only national election we have.”