In a statement released shortly after Abdullah's death was announced, Obama said the king's life "spanned from before the birth of modern Saudi Arabia through its emergence as a critical force within the global economy and a leader among Arab and Islamic nations."
Obama praised the Arab peace initiative that Abdullah proposed in 2002, calling it "an endeavor that will outlive him as an enduring contribution to the search for peace in the region," and credited the leader with forging a strong relationship between Saudi Arabia and the United States.
"The closeness and strength of the partnership between our two countries is part of King Abdullah's legacy," Obama said. "May God grant him peace."
Vice President Joe Biden is expected to lead a delegation to Saudi Arabia in "the coming days," his office said.
In a statement, Biden called Abdullah's death "a great loss for his country."
"It is hard to distinguish him from Saudi Arabia itself," Biden said.
Secretary of State
Former President George H.W.
Bush recalled how the U.S. and Saudi Arabia "stood together against a common foe" after Iraq's 1990 invasion of Kuwait, calling it a "moment of unparalleled cooperation."
"I found His Majesty always to be a wise and reliable ally," Bush said.
Sen. John McCain (R-Ariz.) said Abdullah was an "important voice for reform in Saudi Arabia" who pushed to modernize the nation's education system and brought women the right to vote and run for office.
McCain, who is chairman of the Senate Committee on Armed Services, also called Abdullah a "vocal advocate of peace" and a "critical partner in the war on terror."