The 89-year-old Goldwater has been in declining health for months, the newspaper said, citing sources close to the family. The Associated Press was unable to reach Goldwater's wife, Susan, late Tuesday because nobody answered the telephone at their suburban Phoenix home.
Goldwater biographer Jack Casserly said in September that Goldwater has Alzheimer's disease, a comment the family disputed. Relatives said Goldwater has symptoms of the disease, but they weren't convinced he had Alzheimer's.
In 1996 Goldwater suffered a stroke that damaged the frontal lobe of his brain, which controls memory and personality.
Goldwater was elected to the Senate in 1952, stunning then-Senate Majority Leader Ernest McFarland, a heavily favored Democrat. He gave up his Senate seat for the 1964 presidential bid he lost to Lyndon Johnson.
After winning another Senate term in 1974, Goldwater told President Nixon he faced imminent impeachment amid the Watergate scandal. Nixon subsequently resigned.
Goldwater retired in 1986 after serving five terms. He married Susan Schaffer Wechsler in 1992, when he was 83 and she was 51. He has two sons and two daughters.