A rap song which carries a message of strong support for equal marriage, has reached the top 20 of the Billboard Hot 100 chart.

Rap duo Macklemore and Ryan Lewis released the song Same Love, in February, but as momentum has gained in the campaign for equal marriage across the US, sales have improved, up to last week when it sold 110,000 copies, the most since it was released.

The song, from the pair’s latest album, addresses Macklemore’s personal experiences and feelings around the issue of same-sex relationships and equal marriage, and features a video spanning the lives of a gay couple, including a happy marriage.

The lyrics were inspired by Referendum 74, at which voters in the US state of Washington voted to uphold a law legalising equal marriage.

The song, which also features vocalist Mary Lambert, entered the American Billboard Hot 100 chart recently, despite being released in February this year. Some have attributed its success to momentum gained in equal marriage campaigns leading up to the US Supreme Court’s ruling in favour of same-sex marriage, in two cases last week.

As it approaches a million sales, the song jumped from 28 to 16 in the Hot 100, as well as from 23 to 8 on the US Digital Songs chart.

Macklemore and Ryan Lewis rose to fame last year with the song Thrift Shop, which reached number one in the UK chart. Their follow up Can’t Hold Us, is currently at number 17 of the UK chart, after being in the chart for 16 weeks.

The song Same Love, about equal marriage in the US, which was seen as a positive sign that attitudes towards same-sex marriages are changing for the better, both in the rap industry, and in general, is available to view below.