Although the U.S. Supreme Court struck a mortal blow to the Defense of Marriage Act last week, same-sex marriage is far from settled at the federal level, with lawmakers in Congress responding in different ways.

The court’s twin 5 to 4 decisions overturned a key provision of the federal law and let stand a lower court’s decision against Proposition 8, California’s voter-approved state ban on same-sex marriage. Including California, gay marriage is now legal in 13 states and the District of Columbia.

But the justices left in place bans in at least three dozen states and did not require those states to recognize gay couples married legally elsewhere. Legal experts have said that couples who live in such states may still be denied some federal benefits unless Congress changes the law. And should lawmakers not agree on a solution, the issue will soon be back in court.

Democrats in the Senate and the House, led by Sen. Dianne Feinstein (Calif.) and Rep. Jerrold Nadler (N.Y.), reintroduced a bill to repeal DOMA and erase any lingering uncertainty about which same-sex couples are married in the eyes of the federal government.

“It is time Congress strike this discriminatory law once and for all,” Feinstein said last week, noting that more than 1,100 federal benefits are at stake for married same-sex couples.

Meanwhile, a group of House Republicans, led by Rep. Tim Huelskamp (Kan.), reintroduced a measure to amend the U.S. Constitution to ban same-sex marriage. Huelskamp said the court had “substituted its personal preferences on marriage for the constitutional decisions of the American people and their elected representatives.”

“Congress clearly must respond to these bad decisions,” he added.

The momentum would seem to favor same-sex marriage. A majority of Americans now support it, according to recent polls. And although most Republicans still oppose such unions, the party’s leaders would prefer to move on. House Speaker John A. Boehner (Ohio) spent $2.3 million of taxpayer money defending DOMA in court and lost. He and other Republican leaders say it’s now up to the states.

“The court’s made its decision,” Boehner told reporters last week.

Huelskamp’s effort has 28 co-sponsors. But Boehner and other GOP leaders have not signed on, and it faces long odds anyway, because constitutional amendments require a two-thirds majority in the House and the Senate. The last time the House voted on the Federal Marriage Amendment, in July 2006, it fell short, even with the support of GOP leaders and some Democrats.

Feinstein’s bill, meanwhile, has support from 41 other senators and could gain more. Among the chamber’s 100 members, 54 have declared their support for same-sex marriage, including three Republicans. The House version of the Respect for Marriage Act has 160 co-sponsors, including at least three Republicans.

Brian Moulton, legal director at the Human Rights Campaign, the nation’s largest gay rights group, said it would be difficult to get any legislation passed in Congress to fix what the Supreme Court didn’t. But he added that as more Americans change their minds about same-sex marriage, so will more lawmakers.

Public reaction to Supreme Court rulings

“At some point in the next few years, we’ll reach a tipping point in both chambers,” he said.

— McClatchy Washington Bureau