Archbishop Salvatore Cordileone of San Francisco lead those participating in the March for Marriage in prayer today, as the Supreme Court hears arguments on the first of two cases about gay marriage.

"It is truly inspiring to know that so many people from so many walks of life, including many young people, are expressing their support for marriage," he said of the march.

March 26 is the first day of oral arguments before the Supreme Court in the case Hollingsworth v. Perry. The lawsuit challenges California's Proposition 8, a state measure recognizing marriage as existing solely between a man and a woman.

Hollingsworth v. Perry is one of two cases on same-sex marriage that the Court will consider this year. The other, being argued tomorrow, challenges the Defense of Marriage Act, a federal law defining marriage as the union of one man and one woman.

"It is my hope and prayer that the Supreme Court will uphold Proposition 8 and DOMA, respecting the very nature of the human person and the nature of marriage as the union of one man and one woman," said Archbishop Cordileone, who heads the U.S. bishops' subcommittee on the defense of marriage.

Plans for the the march in downtown Washington, D.C., have generated excitement and enthusiastic support, according to organizers of the event.

The occasion has been hailed as "an opportunity to witness to the culture about our pro-marriage beliefs," according to Thomas Peters, cultural director for the National Organization for Marriage.

Peters told CNA in a February interview that the nation's citizens coming together visibly to support the institution of marriage is critically important.

At 8:30 this morning, march participants met at the National Mall and walked to the Supreme Court Building, where a rally began at 11. In addition to Archbishop Cordileone, speakers include Bill Owens, Sr., founder of the Coalition of African-American Pastors; Eric Teetsel, director of the Manhattan Declaration; and Jennifer Marshall of the Heritage Foundation.

Archbishop Cordileone said that "marriage exists to bring a man and a woman together as husband and wife to be father and mother to children born of their union. The intrinsic dignity of every human being must be affirmed, but this is not realized by redefining marriage to mean simply the public recognition of certain emotional bonds among adults."

"Marriage is rooted in the natural reality that men and women are different, and thereby complementary, and that children deserve both a mother and a father. Respecting this truth benefits everyone."

The two same-sex marriage cases are expected to yield landmark decisions that will set the tone for the definition of marriage throughout the nation.

At the time of going to press, Tom Goldstein, the publisher of SCOTUSblog, tweeted that "There are not 5 votes to strike down Prop 8 and recognize equal right to same-sex marriage at this time."

Goldstein earlier suggested that that it is likely that Hollingsworth v. Perry will be dismissed, leaving in place the Ninth Circuit Court of Appeals' decision in favor of same-sex marriage.

Final decisions in both cases being heard this week are expected in late June.