36 US Code §119 provides that "The President shall issue each year a proclamation designating the first Thursday in May as a National Day of Prayer...." Consistent with that, the non-governmental National Day of Prayer Task Force is promoting today as the National Day of Prayer. However, yesterday (Wednesday) the White House posted a "Presidential Message on National Day of Prayer" (full text) suggesting that yesterday was the National Day of Prayer. The Message, dated May 6, says in part:
This National Day of Prayer, we proudly recommit to our magnificent birthright of faith. I encourage all Americans to come together today in prayer, reflecting on the many blessings God has given our Nation and asking for His continued protection, with ceremonies, events, and programs in their houses of worship and places of work, schools, and homes.
The Message also says in part:
Today, faith in God is resurging on American shores like never before. Throughout this historic year, we rejoice in the triumph of the American spirit and in the love and grace of Almighty God. And just as our Founders came together in prayer before declaring independence, thousands of Americans will gather on Sunday, May 17, on the National Mall to rededicate the United States as One Nation Under God.