You probably know it from the identifiably funky bass line, or its high-reaching falsetto chorus. You might have even heard it in a Vitamin Water commercial starring Aaron Paul or on several late night (and even daytime, thanks to Ellen) talk shows. At this point, Portugal. The Man’s irresistibly groovy hit “Feel It Still” can safely be called inescapable.

But how exactly did this retro-inspired, toe-tapping song from an Alaskan indie band skyrocket into the mainstream -- not to mention, to the top of the Billboard charts, where it has comfortably sat at No. 1 on Alternative Songs for 13 weeks (tying Imagine Dragons' "Believer" for longest streak in the top slot on that chart this year)? "Feel It Still" also reaches a new peak of No. 14 on the Billboard Hot 100 (on the chart dated Sept. 30) -- which has seriously lacked in terms of rock hits this year, save again for "Believer," which broke into the top 10.

“We always look for that lean-forward moment,” Jeff Regan, senior director, music programming at Sirius XM tells Billboard of the song's opening build. “It’s a well-crafted song sonically, but it’s actually the lyric that holds you and keeps you emotionally connected to the song.”

The track's rallying chorus, led by the line “I’m a rebel just for kicks now,” also arrived at a relevant time in terms of America’s political climate -- which frontman John Gourley previously described to Billboard as “a fucking mess.”

Portugal. The Man formed in the early 2000s in Alaska (though has since relocated to Portland, Oregon) and earned minor critical acclaim following its fourth album, 2009's The Satanic Satanist. But even with its growing and faithful fan base, and after making its major label debut on Atlantic with 2011’s In the Mountain in the Cloud -- an album that features fan favorites like the string heavy "So American" and symphonic "Sleep Forever" -- the indie-rockers failed to find chart success. Until now.

Its latest album Woodstock, which features “Feel It Still,” is only the third album released by Atlantic. Regardless, Portugal. The Man has become a top priority for the label. “[This song] is a monster,” Atlantic's GM David Saslow relates, adding when he first heard it late last year that the label unanimously agreed it would be the forthcoming album’s lead single. “When you have a hit song like this, you go with it,” he says.

Regan says after the label came to play “Feel It Still” for him and his team at Sirius back in February of last year, they all had a similar initial reaction to the song’s potential. “We knew all this was going to happen, we could tell,” Regan admits of the single's success. He says the song remains the station’s best-testing and most-requested song -- and it has been for months, even before it topped the Alternative Songs chart.

“We do research on this channel and this has been unlike anything I’ve seen in quite a while,” Regan continues. “This song has afforded the band to be heard not just by an alternative-rock crowd. [Aside from] Alt-Nation, it’s on The Spectrum and Pulse and Hits 1 and our Chill channel. I don’t think there’s any channel here that hasn’t had a massive level of success with this song.”

When asked what other alternative-indie acts come to mind in terms of having similar crossover success, Regan takes a lengthy pause before saying, “Maybe to an extent Cold War Kids… maybe.” Regan also cites Arctic Monkeys, saying, “In the early days they won over the indie rock scene. That last record [AM] took some time, but those songs still to this day resonate great. People aren’t tired of them.” Saslow finds similarities in Fun, a band that released an underappreciated debut (2009's Aim and Ignite) before making it big with crossover smashes like “We Are Young" and “Some Nights.”

Looking ahead to what’s next for Portugal. The Man, Saslow says come November they’ll start pushing the optimistic and rumbling “Live in The Moment” as the album's next single, which Regan says is already off to a great start on radio. Regan also sees potential for the cautionary electric track “Rich Friends” to continue building, too.

“This has been a band that’s been developing for a little over a decade,” Regan emphasizes. “I don’t think there’s fear of the one hit and done, I don’t see any red flags. And they’re good guys, they’ve paid their dues -- they’ve been in the van. You root for so many bands to sustain and even have a chance at a trajectory, [but] not every band is promised that. These guys deserve what they’re seeing right now.”