Barbara Mandrell has become a leading exponent of the crossover phenomenon known as spectrum-pop. She may have started in country when country wasn't cool, but she's gotten progressively hotter and expanded her audience by dishing out a variety of musical styles.

At the Merriweather Post Pavilion last night, Mandrell moved effortlessly from heartfelt country ballads to a tough-as-nails version of Elvis Presley's "All Shook Up," from a Willie Nelson country blues to a rousing black spiritual. On a medley of her "paradox hits" ("Best of Strangers," "Wish You Were Here" and "If Loving You Is Wrong I Don't Want to be Right"), she simply embraced the melodies. At other times the gritty edges of her husky voice crackled with R&B flourishes and gospel fervor. It was an impressive display.

Because Mandrell is an engaging and ebullient performer, it would have been nice to trade in the excessive talk and the unneccessary showcasing of her fine band for a few more songs. Likewise, the inexorable parade of instruments that Mandrell can play only points up that above all she's a powerful singer. Mandrell headlines another show tomorrow afternoon at Bull Run Regional Park in Manassas.