Rural independent Bob Katter says he is "very confident" both houses of Parliament will support a commission of inquiry into the banks he is designing with Nationals MP George Christensen.
Mr Katter said on Monday he would introduce a private member's bill into the House of Representatives next week to create a commission of inquiry into wrongdoing by the banks.
"We are very confident we have the numbers for a majority in the Parliament and in the upper house," Mr Katter said.
"This will be another defeat for the government on a critical issue."
Tasmanian independent Andrew Wilkie appeared beside Mr Katter at a press conference to throw his support behind the bill.
But even if a vote comes before the House, which is far from guaranteed, Mr Katter still appears to be one vote short.
With the support of Labor, Mr Christensen and all the other independents, Mr Katter would still need to convince one other Coalition MP to cross the floor to achieve the required 76 votes.
Queensland Liberal MP Warren Entsch - who previously backed a banking royal commission - said Katter's idea was "bullshit" and he would not support it.
"I'm not interested," he said.
"We know what we need to do; we don't need an inquiry.
"I want a banking tribunal with real powers to hand down enforceable decisions.
"I think Katter's being bloody stupid and a typical populist; this is all about getting his name in the papers."
Mr Christensen, who resigned as chief Nationals whip last month so he could act with more independence, said: "I have said for some time now that I will support a private member's bill that seeks to establish a commission of inquiry".
Mr Katter said Mr Entsch had "dogged" the issue.
"The member for Dawson [Mr Christensen] has not dogged it - he is very well aware of what's happening today and will have a lot of input into what takes place over the next six to eight weeks," he said.
"He has said publicly and privately he will back the bill."
Mr Katter said he expected the matter to come for a vote in the final weeks of May or early June.
Mr Wilkie said: "It does appear the numbers are there to get a bill passed to put weight on the government to have a royal commission."
But he acknowledged the government could block progress by opposing the suspension of standing orders or if the government-dominated selection committee refuses to list the bill for a vote.
"That would mean a government is openly ignoring the majority will of the Parliament and that's downright evil, downright undemocratic," he said.
"The government is totally out of step with the community, which wants a royal commission."
Mr Katter's office said the terms of reference for the inquiry were not ready for release because they were still being finalised with Mr Christensen.
Mr Katter said the inquiry would "have all the powers of a royal commission and then some".