Nick Xenophon has called for a sweeping audit not only of MP citizenship but their financial interests.
The crossbench senator's call comes as two coalition MPs face questions over their eligibility under section 44 of the constitution, which bans from parliament anyone with "any direct or indirect pecuniary interest in any agreement with the public service of the commonwealth".
Labor says Queensland Liberal National Party senator Barry O'Sullivan has serious questions to answer over his possible links to a federally-funded road project.
However, Senator O'Sullivan denies any such links.
Senator Xenophon, who is set to be referred to the High Court over citizenship issues when parliament resumes on September 4, says an audit is needed.
"The sooner we have a sweeping audit, not just of citizenship but also in respect of pecuniary interests, which itself could be going to the High Court, the better off we'll be," he said.
"This could end up paralysing the parliament."
He said the "most powerful element" in Australian politics at present is not an individual or a political party, but section 44 of the constitution.
Senator O'Sullivan owns a portion of a company called Jilbridge Pty Ltd which is declared on his pecuniary interest register.
Jilbridge has a share of O'Sullivan and Sons Pty Ltd, which is a shareholder in Newlands Civil Construction, which is managed by the senator's son.
Last week it emerged Newlands has a four-project contract with Nexus Infrastructure - one of the partners on the Toowoomba Second Range Crossing, a $1.6 billion road bypass.
The federal government is contributing $1.14 billion, or 80 per cent of the project cost, and the Queensland government's share is 20 per cent through a public-private partnership contract.
It is understood the federal funding is combined with state money under the Queensland Transport and Roads Investment Program, and the Queensland government makes payments to Nexus under the PPP contract.
A second coalition MP, David Gillespie, is facing a High Court challenge to his eligibility, after it emerged he owns a shopping centre which has an Australia Post outlet in it.
He has legal advice he is in the clear of any constitutional issues.