Australians will go to the polls on July 2 in the first double dissolution election in almost three decades after the Senate refused to pass a key industrial relations bill designed to boost the regulation of unions.

With Labor and the Greens opposed, and the government needing the support of at least six of the eight Senate independent crossbenchers, the government was two votes short of the numbers required to re-establish the Australian Building and Construction Commission. It was rejected by 36 votes to 34.