Tony Abbott is worried the Senate will keep an "in-built majority for weak populism" under the existing voting system.
The former prime minister says Australia needs to rethink how it wants federal parliament's upper house to run.
"Do we want the Senate to be a house of review, which was what our constitutional founders wanted, or do we want the Senate to be a house of rejection?" he told 2GB radio on Friday.
People frustrated with politics aren't necessarily angry with the major parties, he believes, but more that "good government seems harder than ever".
Prime Minister Malcolm Turnbull called a double dissolution election for July 2, putting all senators up for election instead of the usual half, after the Senate stymied the government's industrial relations plans.
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But voters returned an even bigger crossbench of 11 minor parties and independents, with the government needing support from nine to pass legislation opposed by Labor and the Greens.
That arithmetic has become harder with the resignation of Family First senator Bob Day, and One Nation's Rod Culleton quitting the party to sit as an independent. The election of both senators is being challenged in the High Court.
Mr Abbott, who has previously helped fund legal challenges against One Nation leader Pauline Hanson, now says she's a more mature politician and he believes her party genuinely wants to be constructive.
But the saga with Senator Culleton highlighted the inherent tendency of minor parties to fracture and splinter, he said.
"Even with people who are philosophically inclined towards smaller, better government, there is a tendency to get on your high horse over this or to demand some concession over that," Mr Abbott said.
"That's why government has become a matter of horse-trading and why, as I said, there is an in-built majority for bad government, an in-built majority for weak populism."
