Trace Adkins and Blake Shelton have been close friends for years, but don't look for the roughneck country star to join the coach of The Voice on his hit show anytime soon.

Shelton has often invited his friends and colleagues from country music to mentor the aspiring singers on The Voice, including Luke Bryan, Brad Paisley, Tim McGraw and Faith Hill and Shania Twain.

Shelton has even discussed the possibility of Adkins joining him on The Voice, but "He said I was too mean," Adkins tells Fox News. "He said some of these people are fragile and they don't need to be subjected to me."

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Adkins will hit the small screen on Tuesday (July 4) for A Capitol Fourth, where he will perform his new single, "Still a Soldier," as part of a lineup that includes the Beach Boys, Sugar Ray singer Mark McGrath, the Four Tops, Dan Aykroyd and Jim Belushi of the Blues Brothers and The Voice Season 12 winner Chris Blue, Kellie Pickler, gospel legend Yolanda Adams and two-time Tony Award nominee Laura Osnes. Singer and actor Sofia Carson will perform the National Anthem at the event, which Adkins hopes will help Americans set aside their bitter political divide for a moment.

"The Fourth of July is all about declaring our independence," he says. "We don't depend on anybody else in this world. We make our own way and we have our own freedom, and it is not subject to anybody or anything. That is what this day is about to me, so let's get together, raise a glass and have a good time."

A Capitol Fourth is set to air on PBS live from the West Lawn of the U.S. Capitol in Washington, D.C., on Tuesday at 8PM.

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