Little Big Town's new single 'Girl Crush' has been ranked as the most-added song on country radio this week.

'Girl Crush' is already at No. 55 on Billboard's Country Airplay chart. The tune was penned by Lori McKenna of the songwriting group the Love Junkies, who are responsible for some other LBT songs as well, including 'Sober' from the group's 2012 album 'Tornado,' and 'Tumble and Fall' and 'Save Your Sin,' both off of the recently released 'Pain Killer.'

McKenna says that her writing partners, Liz Rose and Hillary Lindsey, didn't like the idea for 'Girl Crush' at first, but they were convinced after hearing the first verse.

"She gave me this look like she just hated it," McKenna tells Rolling Stone Country of when she first discussed the song with Rose. "She said, 'Lori, shut it down. We're not writing a song called 'Girl Crush.'' She didn't even explain, she just hated it."

But McKenna fought for the song, taking it to Lindsey before giving up on it.

"Liz starts with her argument with the dirty look, and, I'm not kidding, Hillary played the first chord and sang the first verse as it is. And immediately after she sang it, Liz said, 'Oh my god, I love this idea! I get it now, I love it!'" McKenna says. "So we wrote it pretty quickly. And because Liz hated it so much at first, we thought nobody was going to like the song but us, so we weren't careful. It's good for your songwriting soul to write a song that's just for you and isn't commercial."

Little Big Town's Karen Fairchild and Kimberly Schlapman were some of the first people to hear the tune, and they immediately connected with it.

"I knew as soon as I heard the hook of the first chorus that we had to have this song," Fairchild says. "I'd never heard a jealousy song written like this. It's definitely one of the best songs I've ever heard, and to get to sing it every night is a gift.

"It could be a bit of a game changer on country radio right now," she adds. "There are not many women on the radio and not many ballads with that kind of lyrical content. I'm excited. Already, radio's support has been huge out of the gate."