Govt 'Americanising' Aust politics: Labor

Federal Labor has accused the coalition of Americanising Australian politics by using the royal commission into union corruption to attack political opponents.

Labor senator Sam Dastyari says the commission is nothing more than an $80 million political witch hunt by the government.

"What we're starting to see is the Americanisation of Australian politics where you start using the judiciary and these kinds of processes to smear and attack political opponents," he told reporters in Canberra on Monday.

Opposition Leader Bill Shorten has agreed to front the commission to answer questions about his time at the helm of the Australian Workers Union but is refusing to respond before then about alleged sweetheart deals with employers.

Labor senator Doug Cameron said the commission was another attempt by the coalition to reduce wages and conditions after the failure of Work Choices.

"This is nothing but a kangaroo court to attack the trade union movement, to attack individuals and to try and destroy effective trade unionism in this country," he told reporters.