An obscure Midwestern mayor aiming to become America's first openly gay president has surged in polls. Pete Buttigieg, 37, stunned fellow Democrat candidates, leapfrogging many who have vastly more experience on the national stage.

One poll in Iowa, the crucial first state to vote in the 2020 Democrat nomination process, put him in third place behind Joe Biden and Bernie Sanders.

Another national poll had him tied fifth with Elizabeth Warren, the high-profile veteran Massachusetts senator.

What pollsters called the "Buttigieg bounce" was fuelled by a widely praised performance in a CNN town hall event, and the network declared him the "hottest candidate in the race".

A flood of media exposure also included a six-minute laudatory segment on America's The Daily Show. The candidate's book has shot on to the New York Times bestseller list.

Since 2011, Mr Buttigieg has been mayor of his home town of South Bend, Indiana, which has a population of 100,000, and he is widely known there as "Mayor Pete".