Members of President Barack Obama’s party who are running for election in November seek to frame the upcoming vote as one about income and sexual equality. The economy is still foremost on voters’ minds, but Democrats are hoping to change that.

After Vice President Joe Biden told NBC News’ Sunday morning talk show Meet the Press this weekend that he was “absolutely comfortable” with gay marriage, the president, too, voiced support for legalizing marriage for same-sex couples.

No longer “evolving” on the issue, President Obama’s change of heart will likely endear him to young, first time voters who backed him overwhelmingly in 2008 but have since grown weary of his politics.

Among gay Americans, his support of marriage equality is unlikely produce a major shift. In 2004, after President George W. Bush endorsed a constitutional amendment to define marriage as one between a man and a woman, 23 percent of gay Americans voted Republican anyway. In the 2010 congressional elections, 31 percent did.

While 50 percent of the general population supports gay marriage, 70 percent of Americans under the age of thirty does. Two thirds of them voted for Obama in 2008.

The president’s election year conversion on the issue of marriage appears to be part of a concentrated effort to frame the upcoming vote as one between the progressive Barack Obama who tries to move the nation “forward” and intransigent Republicans who, on both economic and social issues, are “backward” in their opposition to his policies.

It’s not just on marriage that Republicans are supposed to be reactionary. Democrats accused conservative lawmakers of waging a “war on women” earlier this year because they did not want to force insurance companies to include birth control in their mandated coverage.

The fight over contraception was “illuminating,” the president told a group of women voters last month. “It was like being in a time machine.” He added, “The choice between going backward or moving forward has never been so clear.”

Obama is currently leading his likely Republican opponent Mitt Romney among woman 49 to 39 percent.

Besides marriage and gender equality, the president has described mounting income inequality as “the defining issue of our time.” Few Americans agree. In a recent Gallup poll, just 2 percent of respondents listed the gap between the rich and poor as their top economic concern. But there is a sense that opportunity is increasingly denied to the middle class while the wealthy are shielded by their Republican friends from higher taxes and regulations.

So Republicans, again, have it backward when they want to lower taxes on businesses and high-income earners but privatize federal health support for seniors at the same time. As the president put it, they want “everybody left to fend for themselves and play by their own rules.”

The fact that Mitt Romney seems rather more like a character out of the popular drama series Mad Men, set in the 1960s, socially awkward and unsentimental when he talks about the economy, doesn’t help.

Voters overwhelmingly see joblessness and the ballooning national debt, areas in which the president has made markedly little progress, as the most important issues for the upcoming election. Democrats, who have resisted every Republican effort to rein in spending and not even introduced a budget in the Senate for all of Obama’s presidency, know that they cannot win on the economy. They have to change the conversation.

A majority of Americans is now on the left on most social issues, except abortion. Opposition to contraception coverage and gay marriage is concentrated in conservative states that are safely Republican. In critical swing states like Ohio, Pennsylvania and Florida, which will likely determine the outcome of November’s presidential election, voters lean Republican on economic issues but may well give Democrats a majority if they see the other party as backward indeed.

If Republicans fall for this trap and lose sight of their potentially winning argument — that they’ll fix the economy and get the government’s fiscal house in order — to revive the culture wars of the 1990s, this time, they will probably lose.