A long-time friend of Rev. Billy Graham says the  90-year-old evangelist is having trouble speaking.

In a recent interview with Minnesota's KTIS Radio, Rev. Jack Hayford said Graham "can hardly talk now."

"You can understand him, but he could not get up and speak before a group," Hayford explained.

The evangelical leader, who is best known for bringing millions to Christ during his "Billy Graham Crusades," now uses a walker and has been in and out of the hospital in recent years.

Graham's spokesman, Larry Ross, confirmed that he does have bouts of weakness, but is lucid and remains interested in current events.

Graham has not preached publicly since 2006, but his son Franklin has said the family is helping him work on a book about aging.

During the celebration of his 90th birthday November 2008, Graham's son revealed, "He has said several times, 'Franklin, I wish I had the strength to do one more crusade.'"

Franklin Graham has lead the Billy Graham Evangelical Association since his father stepped down in 2006.

Sources: Associated Press, Christianity Today