The Supreme Court will announce their decision on the fate of marriage in the U.S. It’s a big day.

The National Organization for Marriage is asking marriage supporters in the D.C. area to amass outside the Supreme Court:

Tomorrow is D-Day for marriage. In this case, “D-Day” means “Decision Day.” The marriage cases were not decided today, but Chief Justice John Roberts announced that the decisions will be issued tomorrow, which will be the Court’s last day in session for this term.

We at NOM remain optimistic. Of course, the Supreme Court should uphold both Proposition 8 and the Defense of Marriage Act. Of the two cases, the Prop 8 case is definitely the most important. If Prop 8 is upheld, it means the Court has found no constitutional right to same-sex marriage, and all the traditional marriage laws in America will be preserved. It’s the end of the claim that same-sex marriage is somehow “inevitable.” Gay ‘marriage’ activists will have suffered a catastrophic loss. We feel good about the likelihood of prevailing on Proposition 8.

If you can get there, please join other supporters of marriage on the steps of the US Supreme Court tomorrow morning at 9:30am. The remaining decisions will begin coming down at 10:00am eastern, so we should know the outcome soon thereafter.

No matter what the Supreme Court does tomorrow, the battle to preserve marriage as God designed it will continue. We ask that you pray this evening for the success of our position before the Supreme Court, for the attorneys and their families who have sacrificed so much to fight for the truth of marriage, and for those of us who will be in the media firestorm tomorrow reacting to whatever the decision may be.

You’ve got prognosticators on both sides making all sorts of predictions. The fact is, nobody knows anything. So say a few prayers and wait until tomorrow. Check back here. We’ll be on it.