By Tom Curry, msnbc.com National Affairs Writer

President Barack Obama’s words of personal support Wednesday for same-sex marriages doesn’t change the laws in 38 states that define marriage as a union between one man and one woman.

Obama aides told The Associated Press that he continues to believe that marriage is an issue best decided by the states. But the president’s comments are also a reminder that at least some aspects of the marriage issue will almost certainly be decided by federal judges, not voters.

For example, there’s ongoing litigation in two federal appeals courts over the constitutionality of the 1996 law signed by President Bill Clinton, the Defense of Marriage Act.

The plaintiffs contend that the law violates the U.S. Constitution’s guarantee of equal protection by requiring the federal government to deny recognition of the legal marriages of same-sex couples in Massachusetts and other states.

The high court may also decide whether to hear a case from California on the constitutionality of Proposition 8, approved by voters in 2008, which amends the state constitution to define marriage in traditional terms.

Who will be the judges and justices who will decide these cases?

That will partly be decided by the voters in November – will it be Obama or Republican Republican Mitt Romney who will have the power to nominate judges over the next four years?

Voters will also decide whether it will be a Democratic-controlled or a Republican-controlled Senate that will be voting on whether to confirm those judicial nominees.

With Justice Ruth Bader Ginsburg at age 79, Justice Antonin Scalia 76, and Justice Anthony Kennedy 75, it’s entirely possible the next president could appoint two or three justices, as well as dozens of judges to the appeals courts.

To see how high the stakes are, look at the cases before the high court over next couple of years:

• The validity of a crucial section of the 1965 Voting Rights Act (the Shelby County, Ala. case now being considered by a three-judge panel in the court of appeals in Washington, D.C., Circuit);
• More appeals from prisoners being held by the United States at the Guantanamo base;
• And perhaps another immigration battle – especially if the high court splits 4-4 in the Arizona case in which it heard oral arguments last month.

Already on the docket for the Supreme Court term starting in October is a case concerning the use of race and ethnicity as factors in the admissions policy at the University of Texas.

By the time voters cast their ballots in November the court will have delivered its rulings in the challenges to Obama’s landmark health care overhaul and to the Arizona immigration law.

“You really have this amazing combination of not just legally important but politically charged, one might even say divisive, issues all before the court right before the election,” said Curt Levey, executive director of The Committee for Justice, a conservative group that tracks judicial nominations.

“As we get closer to the election and we have these decisions, I think there’s no way to avoid it being one of the top issues in the campaign.” 

Some conservatives are chilly toward Romney because they doubt he’s genuinely committed to their principles. But when it comes to judicial nominees, Levey said, “I think it’s clear just from his public statements that he realizes that this is a key issue for conservatives. Even if you are a conservative cynic about Romney and don’t believe that he’s a real conservative, I think you can be reassured that – taking the cynical point of view – he certainly has to throw some bones to conservatives.”

Asked to name his favorite Supreme Court justice in a FOX News debate last December, Romney named four: Scalia, Chief Justice John Roberts, Justice Clarence Thomas, and Justice Samuel Alito – all Republican appointees. 

Progressives, of course, also recognize the consequences for the courts of what voters decide in November.

Judith Schaeffer, vice president of the Constitutional Accountability Center, a progressive think tank said: “With the Supreme Court as starkly divided ideologically as it is today, the stakes this November are quite high. On so many issues of critical importance, the Constitution truly is at a crossroads before the Court under Chief Justice John Roberts. That said, every presidential election is important to the future of the federal judiciary, given the President’s constitutional responsibility to nominate Supreme Court Justices and lower court judges.”

There’s a pent-up frustration among Democrats that Obama has not been able to get more of his judicial nominees confirmed by the Senate. According to the liberal group Alliance for Justice, there are now 15 vacancies on the federal courts of appeals and 78 district court vacancies.

“Until this month, the number of vacancies on the federal courts had stood at 80 or more for more than 1,000 days, a harmful vacancy crisis caused by unprecedented obstruction of the president’s nominees by conservatives in the Senate. Progressives, like most Americans, are tired of the gridlock in Washington, which has left the third branch of government one of its worst casualties,” Schaeffer said.

Obama has appointed 144 of the judges and justices now serving on the federal bench. In his first term, George W. Bush had 204 confirmed, according to the Federal Judicial Center.