SANTA ANA, Calif. — Former first lady Nancy Reagan planned to endorse John McCain for president on Tuesday, as the Arizona senator continued to collect the backing of leading Republicans who might help him win over critical conservative voters.

Now certain to win the GOP nomination, McCain is on the west coast this week to raise money. He was to stop by the Southern California home of former President Ronald Reagan’s widow to accept her endorsement.

In a statement before the event, Reagan said she typically waits until after the GOP convention to announce her support but she decided to do so now because it is clear the Republican Party has chosen its nominee.

“John McCain has been a good friend for over thirty years,” Reagan said. “My husband and I first came to know him as a returning Vietnam War POW, and were impressed by the courage he had shown through his terrible ordeal. I believe John’s record and experience have prepared him well to be our next president.”

Reagan’s eventual support was expected, and she will become the latest Republican heavyweight to fall in line behind McCain. She and McCain have long been close, and it was only a matter of time before she spoke up for her friend.