It's something voters in the US may not have expected to hear during the fight for the Democratic presidential nomination: Australian accents.

While a shrinking field of candidates battle for the chance to take on President Donald Trump, a bunch of Bernie Sanders' Melbourne supporters – the "MelBerniens" – have been campaigning for the 78-year-old Vermont senator from the other side of the world.

Ryan Mickler and Tharini Rouwette from the MelBerniens. Credit:Justin McManus

Brunswick man Ryan Mickler isn't American and can't vote but he was up early on Wednesday cold calling people in California and Texas through an online campaign tool known as "the Bernie dialler" to drum up support for Mr Sanders.

Using another mass-texting app called Spoke, the 34-year-old tech startup worker also sent thousands of messages ahead of "Super Tuesday" in the US, when 14 states held Democratic primaries.