Crossbench senators with the power to kill off Coalition's company tax cuts have warned a string of damning revelations out of the banking royal commission undermines Prime Minister Malcolm Turnbull's flagship policy.

Senator Tim Storer, who with fellow independent Derryn Hinch holds the power to block the $35.6 billion package when Parliament resumes next month, stopped short of directly linking the damaging evidence to his ultimate decision, maintaining the issues were "separate and distinct".

"But in the public eye, the behaviour of some of Australia’s biggest and most privileged companies is obviously not going to help the government’s case," Senator Storer told Fairfax Media.

The Coalition had hoped to resume negotiations with the Senate when Parliament resumes in May. However some MPs privately fear corporate and even criminal misconduct outlined at the banking royal commission this week threatens to undermine public support for the package, which would eventually shave billions from the tax liability of some of Australia's largest financial institutions over the next decade.

Labelling the banks "crooks", Senator Hinch hardened his resolve on Friday and vowed to not support the government's plan unless the banks were excluded.