Deputy Liberal leader and Treasurer Josh Frydenberg has cancelled a planned trip to the G20 economic forum in Buenos Aires this week amid the chaos engulfing the Liberal Party and the Federal Parliament.

Mr Frydenberg, the most senior Victorian member of the federal Coalition, is managing the fallout of the Liberals' disastrous showing at the weekend's state election, as well as the defection of former Liberal MP Julia Banks to sit on the crossbench on Tuesday.

Treasurer Josh Frydenberg and Prime Minister Scott Morrison in Canberra on Tuesday. Credit:Dominic Lorrimer

A spokesman for Mr Frydenberg confirmed he would no longer attend the G20 leaders' forum, which starts on Friday. Finance Minister Mathias Cormann - who has attended the past three G20 leaders' summits - will now attend instead.

Prime Minister Scott Morrison will also still attend, though he was not on the list of those planned to have bilateral meetings with US President Donald Trump that was announced by the White House overnight.