President Barack Obama offered appreciation and prayers on behalf of all Americans to Pope Benedict XVI, following the pontiff's shock announcement on Monday that he would resign.
"The Church plays a critical role in the United States and the world, and I wish the best to those who will soon gather to choose His Holiness Pope Benedict XVI's successor," Obama said in a written statement.
"Michelle and I wish to extend our appreciation and prayers to His Holiness Pope Benedict XVI."
The president said the first couple warmly remembered meeting the pope in 2009.
US Secretary of State John Kerry, a Catholic, praised the pope as a "man of action and principle, working to promote human rights and dignity in places around the globe where they are too often denied, and a voice of clarity and conviction about our obligations as stewards of a fragile planet."
"We have been honored to work with the Holy See during the nearly eight years of his papacy and look forward to continued collaboration in areas of common interest to our nation and to the Catholic Church," he added.
"We wish Pope Benedict great peace and health and we will keep him in our prayers."
The pope announced earlier that he will resign because of old age, becoming the first pontiff in 700 years to step down in a move that stunned the world.