The overwhelming majority of domestic violence victims are women — a crucial constituency this presidential and congressional election year and one without which Obama would not be president. The renewal of the act, reauthorized twice with overwhelming bipartisan support, is the latest example of partisan warfare this year over women’s issues that have won wide agreement in the past.

The Violence Against Women Act was established in 1994 to provide taxpayer money for the prevention of domestic abuse and the protection of victims. The last reauthorization, in 2005, expired in 2011.

Sensing political gain by bringing up the reauthorization in an election year, majority Democrats in the Senate expanded it to specifically protect gays, lesbians, bisexuals and transgender Americans from discrimination and abuse in a move many Republicans saw as a provocation to vote against a bill approved without objection in the past.

Senate Republicans also objected to Democratic provisions in the bill that would give tribal authorities the power to prosecute non-Indians for abuse committed on tribal lands, saying it was unconstitutional because the accused would have no role in shaping laws that could be used against them.

The Senate bill passed, 68-31, with 15 Republicans voting yes.

A Republican-written House version, now revised, is strongly opposed by an armada of advocacy groups for women, gays and Native Americans.

It omits the Senate’s references to gays, lesbians, bisexuals and transgenders and does not allow Native American authorities to prosecute non-Indians who commit abuse on tribal land.

The new version does restore confidentiality for immigrant victims of abuse, according to a Democratic official who was not authorized to speak on the issue publicly. But the White House said it still allows abusers to become aware of their victims’ allegations.

And it allows a battered Native American woman or a tribe on her behalf to file in U.S. District Court for a protection order against an alleged abuser, whether Indian or not, who committed the abuse on Indian land. But the White House and other Democrats want tribal courts to be able to prosecute the offenders, a proposal Republicans insist is unconstitutional.

Objections to the GOP-written bill also came from a small group of Republicans who urged the House to consider a bill that could gain a measure of bipartisanship.

Rep. Judy Biggert, R-Ill., told the House Rules Committee late Tuesday that the bill should look more like the Senate measure on the immigrant and LGBT provisions.

“I am very concerned that the current bill, even with changes made … doesn’t reflect everything we’ve learned over the last five years in terms of what works best for prosecutors or victims,” Biggert told the panel.

If the House bill passes, a committee of lawmakers from both chambers is expected to work out differences.

“I’m going to stay focused on jobs, thanks,” House Speaker John Boehner, R-Ohio, said repeatedly when asked about Obama’s announcement on gay marriage. “The president can talk about it all he wants. I’m going to stay focused on what the American people want us to stay focused on.”

Romney is taking a similar approach, avoiding any discussion of the issue unless he’s questioned about it and focusing on the economy.

“It’s hard right now. It’s real tough,” he said Friday in Charlotte, N.C. “It’s because of the wrong policies. The right policies are going to put America back to work and make us the economic powerhouse we’ve always been.”

While Republican activists acknowledge that the economy is the top concern for voters, they also see the night-and-day contrast between Obama and Romney on gay marriage as being too good not to exploit at the right times, in the right places. On questions of whether Romney’s sufficiently conservative, for example. Or on the subject of consistency.

Particularly appealing, some activists said, was the White House’s notion that Obama’s “evolution” on the issue is somehow different from flip-flopping.

“This is one situation where Obama looks like the flip-flopper and Romney looks consistent,” said Ralph Reed, president of the Faith & Freedom Coalition, a conservative, grass-roots advocacy group. “So much for the notion that Romney’s the one with no core.”

Romney has taken heat from Democrats and some Republicans for changing his position on some issues, such as abortion. But the former Massachusetts governor has not done so on gay marriage. He has been consistent in saying he believes marriage is between a man and a woman.

Obama held an identical position through his 2008 election, but he said in late 2010 that his views were “constantly evolving.” Feeling pressured by events this week, Obama announced his new position Wednesday.

Before Obama went on record in support of same-sex marriage, Vice President Joe Biden last Sunday pronounced himself “absolutely comfortable” with men marrying men and women marrying women. Then on Monday, Education Secretary Arne Duncan said he supports gay marriage, too. The next day, voters in North Carolina approved a constitutional amendment banning gay nuptials, making it the 30th state to do so.

Besides the political and financial value of the issue, Republicans see a geographic benefit since several of the states that will decide the White House race have banned gay marriage in some form. In Ohio, Florida, Nevada and Virginia, for example, highlighting Obama’s embrace of gay marriage and Romney’s opposition to it could help energize conservative constituencies and win over right-leaning independents.

“This isn’t going to be the No. 1 issue in the campaign, but it’s going to mean a point or two in some of those selected states,” said Richard Viguerie, a longtime conservative fundraiser. “Conservatives are going to be methodical about it, working in the churches and doing groups on the ground.”

Activists are racing to turn emotions into contributions for grass-roots organizing and ads and, in November, votes.

“President Obama has made this an issue in the campaign and we are confident that Mitt Romney will eagerly defend the voters of these states against the president’s attempt to impose same-sex marriage on the nation,” said Brian S. Brown, president of the National Organization for Marriage.

Groups focused on a broader portfolio of issues say gay marriage will be one of several social issues on their agendas but that none will be emphasized as prominently as Obama’s performance on the economy.

Before Obama’s announcement, Reed’s Faith & Freedom Coalition was preparing a voter guide and social media campaign that included gay marriage with other social issues.

“The only thing that’s changed now is that we can say that Obama himself has come out and stated that he’s for single-sex marriage,” Reed said.

Roberta Combs, president of the Christian Coalition of America, a conservative grass-roots group, didn’t need Boehner’s counsel to know that Obama’s support for gay marriage shouldn’t play a leading role in the election. She’s seen the polls that show America roughly split over gay marriage, although with support for it growing, as well as surveys that leave no doubt voters remain jittery about the economy and their personal finances.

“I don’t want to see the election just based around social issues,” Combs said. “You can’t keep Americans’ minds off of the economy.”