NASHVILLE — Country artists Brooks & Dunn, Lee Greenwood, Hank Williams Jr. and Lorrie Morgan — with their favored themes of God, country and the common man — have been tapped for key performances during the Republican National Convention, which expects 45,000 attendees this week in Philadelphia.

This event marks the fourth Republican convention for singer/songwriter Greenwood, who will sing his patriotic trademark "God Bless the U.S.A." at a key moment on Wednesday at 11 p.m. EDT.

"We got a phone call from the GOP, and they said, 'Secretary [Richard] Cheney would like to request Lee [Greenwood] to perform immediately following his [vice presidential nomination] acceptance speech,' " said Jerry Bentley, Greenwood's manager.

Acclaimed honky-tonk duo Brooks & Dunn also will hit the stage for an important performance Thursday night. They'll jam on the blue-collar tune "Hard Workin' Man" (RealAudio excerpt) around 10 p.m. EDT, before Texas Gov. George W. Bush's nomination acceptance speech.

Morgan was first asked to appear at a Thursday afternoon luncheon for the National Federation of Republican Women. Then she was invited to stay and sing the national anthem that evening.

"I was asked to entertain at Mrs. Bush's request, and that was certainly quite a flattering invitation," said Morgan, who will appear just after 7 p.m. EDT.

Williams made an unscheduled appearance Monday night, doing a rousing parody of his famed "Monday Night Football" theme song "All My Rowdy Friends Are Coming Over Tonight," redone as "All My Rowdy Republican Friends Are Coming Over Tonight."

Williams had played at former President Richard Nixon's re-election party, but this was his first convention appearance, said Merle Kilgore, his manager. Kilgore also said the call from the Republicans came out of the blue.

Wynonna Judd also has joined in the festivities, playing a private engagement Monday evening sponsored by Oklahoma Sen. Don Nickles at the Hard Rock Café. The acoustic performance featured Wynonna backed by three guitarists and three backup vocalists.

GOP ties to country music go far back. In 1948, the then-"King of Country Music" Roy Acuff ran for governor of Tennessee on the Republican ticket. Though unsuccessful in politics, Acuff became the first living member of the Country Music Hall of Fame in 1962.

Acuff kept up political connections, however, including his friendship with President Nixon who, in 1974 while still in office, appeared onstage with Acuff to help inaugurate the new Grand Ole Opry House. On the stage, Nixon spoke glowingly of the shared family values of country music and the Republican party.

In the 1980s and '90s, these two worlds continued to intermingle.

Tennessee politicians, including Gov. Don Sundquist and Sen. Fred Thompson, are regular guests at country music functions.

Former President George Bush attended a roast in Acuff's honor in 1981, and he and his wife attended the Country Music Association awards show in 1991. The couple also appeared at the 1996 pre-opening celebration for Greenwood's musical theater in east Tennessee.

But the relationship between Republicans and country musicians hasn't always been smooth. In 1997 Willie Nelson and Jimmie Dale Gilmore were among artists who submitted letters protesting an action of George W. Bush. The musicians opposed Bush's intent to sign a bill prohibiting Texas state agencies from investing in conglomerates that owned more than 10 percent of companies with record labels that release explicit recordings.