WASHINGTON, Jan. 16 (RNS) -- Evangelist Franklin Graham will take the place of his father, Billy Graham, and give the invocation at the swearing-in ofPresident-elect George W. Bush because the elder Graham is ill.

A. Larry Ross, Billy Graham's spokesman, said Tuesday theelder evangelist is undergoing medical tests and awaiting surgery tocontinue treatment for the buildup of fluid on his brain.

"Tests that were conducted last week and over the weekend revealedthat the shunt inserted this summer to treat normal pressurehydrocephalus is not functioning properly," Ross said.

Graham has had a role in eight presidential inaugural events,including giving the invocation and benediction at the 1989 inauguralceremony of Bush's father, George Herbert Walker Bush.

"I consider it a great privilege to have been invited byPresident-elect Bush to participate in his inaugural ceremony," Billy Grahamsaid in a statement. "I love and respect his entire family very much,and regret that I am not able to join them for this special occasion."

In addition to giving the invocation at the swearing-in on Saturday,Franklin Graham also will preach the sermon at the inaugural prayerservice set for Sunday at the Washington National Cathedral.

"He's honored and excited about it," said Mark DeMoss, FranklinGraham's spokesman. "It's a great opportunity, a rare opportunity, andis something he's taking very seriously. He pretty much cleared hisschedule this week to work on both of these."

Ross said the elder Graham had been invited to speak at thecathedral service but had declined "to conserve his energy." Graham hadhoped to sit with the Bush family during the service.

"Obviously, of course, he's disappointed that he can't be inWashington on this special occasion, not only for our nation, but forthe Bush family with whom he's had a warm friendship for many years,"Ross said. "At the same time, he and his wife Ruth ... are very proudthat their son Franklin can offer the inaugural prayer in his place."

The Rev. Kirbyjon Caldwell, an African-American pastor who leadsWindsor Village United Methodist Church in Houston, is scheduled to givethe benediction at the swearing-in and is among the list of participantsfrom a variety of faiths at the cathedral service.

Other scheduled participants at the service include Greek OrthodoxArchbishop Demetrios; Roman Catholic Archbishop Theodore McCarrick ofWashington; Pentecostal minister Jack Hayford, founding pastor of theChurch on the Way in Los Angeles; and contemporary Christian singerMichael W. Smith.