Tammy Baldwin (D-Wisc.) celebrates her victory over Republican candidate Tommy Thompson as she enters the stage on election night in Madison. Baldwin will now be the first openly gay member of the U.S. Senate. (Darren Hauck/Getty Images)

Just before Tuesday’s elections, a national gay-rights group sent its supporters in Maryland an e-mail listing an additional reason to go to the polls to approve same-sex marriage.

“Justice Anthony Kennedy is watching you,” the subject line said.

What Kennedy and the rest of the Supreme Court saw was by all accounts a momentous day for gay rights and same-sex marriage.

The country reelected a president who has “evolved” enough on the issue to support gay marriage. Wisconsin elected Democrat Tammy Baldwin, who will be the first openly gay member of the U.S. Senate.

Iowa, which two years ago voted out three state supreme court justices who ruled that homosexuals must be allowed to marry in the state, reversed course. It retained a fourth justice who had joined in the decision after a spirited campaign to oust him.

Maryland, Maine and Washington became the first states to approve same-sex marriage through popular vote, rather than a decision of the legislature or the courts. Minnesota defeated an attempt to amend the state constitution to prohibit same-sex marriage, the first time such an attempt has failed at the ballot box.

“The justices obviously pay attention,” said Chad Griffin, president of the Human Rights Campaign, a gay-rights organization.

But, with the court on the cusp of its most serious examination of the constitutional issues surrounding same-sex marriage, it is unclear what the justices heard.

They will soon sort through a half-dozen cases that raise the issue of same-sex relationships; the date for their private conference on whether to accept any has been rescheduled for Nov. 30.

Most of the cases involve the Defense of Marriage Act (DOMA), passed in 1996 to bar the federal government from recognizing same-sex marriages performed in states where it is legal. The Obama administration no longer defends the law, and every court that has heard a challenge has found it unconstitutional.

The justices also have in front of them the decision by the U.S. Court of Appeals for the 9th Circuit to overturn Proposition 8, in which Californians changed their state constitution to remove a right to same-sex marriage the state supreme court recognized.

And the same appeals court has blocked an Arizona law that rescinded the extension of certain benefits to the domestic partners of state employees.

Tuesday’s ballot results are prompting some nuanced responses from those on both sides of the issue.

Supporters of same-sex marriage say the votes — along with polls showing acceptance of gay marriage high among younger Americans — point to inevitable momentum, but not so much that the court should leave the question of equal rights to the political process.

“At the end of the day, it’s the reason we have the judiciary — to protect the rights of the minority,” Griffin said.

Those opposed to same-sex marriage say that Tuesday’s votes show gays are hardly powerless in the political arena, and the court would be unwise to disrupt the process with, for instance, a finding that there is a constitutional right to marry.

“The culture wars would just blow up,” said John C. Eastman, a professor at Chapman University School of Law and chairman of the board of the National Organization for Marriage, which opposes same-sex unions. “I’ve lived this for 30 years on the abortion issue.”

The Proposition 8 case was decided by the appeals court in a way that sidestepped the question of whether the constitution requires that gays be allowed to marry, and would reinstate same-sex unions only in California. That might be reason not to accept the case.

Or the justices could choose to review it and decide it along the same narrow grounds as the appeals court.

But the court is almost obligated to take one or more of the DOMA cases. As the state of play now stands, it would be unconstitutional to withhold federal recognition — there are more than 1,100 references to marriage in federal laws, codes and regulations — to same-sex couples married in the Northeast states covered by the U.S. Courts of Appeals for the 1st and 2nd circuits. But the decisions don’t apply to those married in Iowa, the District of Columbia or those states that Tuesday approved gay marriage.

About 15 percent of Americans now live in states that allow gay marriage, and the number would double if the right were reinstated in California.

The gay rights group Courage Campaign, which sent the e-mail about Kennedy, is right that he is the justice most think will control how the court decides the issues. He wrote the court’s most important gay-rights case to date, striking down sodomy laws.

Kennedy also tends to take into account society’s shifting views on social issues. But Eastman said that Tuesday’s votes in several liberal states is hardly decisive.

“I don’t think three states [approving same-sex marriage] out of 35 states that considered it is going to be the kind of trend that affects the court,” he said. Just six months ago, more than 60 percent of North Carolinians changed their constitution to prohibit same-sex marriage.

Pamela Harris, a student of the court who worked in the Obama Department of Justice and now teaches at Georgetown University Law Center, believes there is another justice to consider.

She thinks Chief Justice John G. Roberts Jr. will want to be cautious about the court taking a bold stand on an issue in which public opinion seems to shift quickly.

Harris is hardly disinterested, she noted: She spent the past month working to see same-sex marriage approved in Maryland.

“I think the tide of history is going one way,” she said. “I don’t think the justices want to be on the wrong side of that.”