Jessica Simpson has made converts of country music fans with “Come On Over,” the debut single from her forthcoming album, Do You Know. The song has made it into the top 25 on Billboard’s country singles chart.

AP / Bill Waugh

When Jessica Simpson announced plans to go country after her last pop album flopped, there was a collective eye roll in Nashville.

To some skeptics, it appeared to be a calculated move to follow in the footsteps of other pop stars who have found success by crossing over to country radio. After lackluster album sales, acting disappointments and bad press over her high-profile romances, Simpson certainly needed a boost.

But “Come On Over,” Simpson’s debut single from her upcoming country album, is not only winning over those same skeptics, it’s gaining ground on country radio. A flirtatious, steel-guitar-laced slice of pop country, the song has cracked the top 25 on Billboard’s country singles chart.

“The best way to sum this up is what program directors have been telling our promotions staff: ‘I really wanted to hate this record, and I don’t. I love this,’ ” said Tom Baldrica, vice president of marketing for her label, Sony BMG Nashville.

Despite her crossover potential, that’s not what the label or the Texas-born Simpson seem to have in mind with the single, which was co-produced by John Shanks, who’s also worked with Sheryl Crow, Michelle Branch and Melissa Etheridge.

“If other folks want to play it, we’re not telling them not to,” Baldrica said, “but our focus is on country. We want to make sure she’s in this format because this is where she belongs.”

John Hart, a Nashville-based marketing researcher, says the song appeals to young, active listeners, who are more likely to call radio stations and attend concerts and events. It tested in the top five in his online sampling the past few weeks and also did well in random telephone surveys that reach country’s more traditional base.

“I don’t think people were anticipating the song to be that good,” said John Paul, program director at KUPL in Portland, Ore. His station has been playing the song for two weeks in light rotation.

“It’s a good song regardless of who sings it, but having her sing it — whether you like her or hate her, everybody knows who Jessica Simpson is,” he said. “And I think there’s a lot of credibility that she co-wrote the song.”

Country fans have seen a steady parade of artists from outside the genre. The Eagles, John Mellencamp and Bon Jovi made inroads, and Simpson is currently joined on the upper half of the chart by Jewel and Hootie & the Blowfish frontman Darius Rucker.

But Simpson, 27, may have a special challenge because of her tabloid persona. These days, the pop star/reality star/movie actress is better known for her relationships (Dallas Cowboys quarterback Tony Romo is her current beau) than her music.

“We were certainly aware of that and knew that it would be an issue in some places,” Baldrica said. “But like everything, if you have it in the music then everything else has a tendency to take care of itself.”

Simpson comes to country after her last pop album was a commercial and critical failure — it sold just 299,000 copies, according to Nielsen SoundScan. The album Do You Know is expected to be released in September; the title track was written by Dolly Parton, who sings background vocals.

For her part, Simpson is promoting the song pretty much the same as any new country singer: She courted fans at last month’s Country Music Association festival, in Nashville, and will perform at state fairs and visit radio stations.

“She’s done what a lot of newcomers and established stars have done by putting out fun, up-tempo, put-the-top-down and cruise type songs,” remarked David Scarlett, senior editor of Country Weekly magazine. “It’s a great way to introduce herself. I think country audiences will be receptive based on the music they hear. If they like what they hear, they’re going to embrace her. And so far, she’s done very well.”