Former first lady Nancy Reagan, the steadfast partner of the 40th U.S. President Ronald Reagan, has died of heart failure at the age of 94.
Entertainment news site TMZ first reported her death in Bel-Air, California, on Sunday.
The actors-turned-first couple were married for more than a half-century, occupying the White House from 1981 to 1989.
As a Hollywood B-movie actress in the 1940s, Ann Francis Robbins – known on stage as Nancy Davis – crossed paths with Ronald Reagan, then also an actor. She affectionately called him "Ronnie." The couple married in 1952.
Her husband was governor of California from 1967 to 1975. Following a failed presidential bid in 1976, he subsequently won back-to-back elections in the 1980s.
WATCH: Related video of Nancy Reagan
As first lady, she spearheaded the "Just Say No to Drugs" campaign against substance abuse, carving a space for herself in the national movement to combat recreational drugs.
A regular presence by her husband's side, Nancy Reagan was also sharply criticized for extravagant spending at the White House at a time of high unemployment in the U.S.
By all accounts, the couple remained close until the former president died in 2004 after a decade of living with Alzheimer's disease, a progressive brain disorder that has no cure.
Nancy Reagan will be buried beside her husband at the Ronald Reagan Presidential Library in Simi Valley, California.
They are survived by two children, Patti Davis and Ron Reagan.
This is a breaking news story; please check back for updates.