The federal government plans to set a start date of the middle of the next parliamentary term for the commencement of its electoral reforms, which would cap election spending and donations.

But it has delayed the introduction of the legislation from the sitting fortnight starting next week until the sitting starting September 9.

The delay is because of the significant and complicated drafting of the legislation and, in particular, obtaining further advice in relation to the constitutionality of the spending caps. These could face challenge in the High Court on the grounds of limiting political communication.

Special Minister of State Don Farrell will have further discussions next week with parliamentary colleagues, including the opposition, the Greens and crossbenchers. He aims to show them in confidence the draft bill.

The best outcome for the government would be an agreement with the Liberals, but so far there is no deal. Several “teal” MPs are suspicious of the government’s intentions because they feel the reformed system would be likely to inhibit new and small players.

Under extensive changes, political donations would need to be disclosed in “real time” during elections. Spending on individual seat campaigns would be restricted to an amount expected to be less than $1 million per candidate.

Originally, Farrell had hoped to get the new regime in place before the coming election. But the extended timetable will give the parties and candidates a longer opportunity to prepare for the change, which might make the package’s passage through parliament easier.

It would also provide the Australian Electoral Commission – already busy with preparations for the coming election – with plenty of time to upgrade its IT systems.

Government sources say there will be significant penalties for breaches of the regime, so there is an advantage in having a longer preparation period.

The government would like to get the legislation through parliament in the mid-September sitting fortnight, but this would seem very unlikely because a parliamentary inquiry would probably be sought. The government’s fallback is for passage in October, which could still be overly optimistic.

Farrell said on Tuesday: “I am not shying away from what could be an opportunity for world-leading reform.”

He said Australia had an electoral system “that is the envy of the modern world, but the system is not perfect.

"It can and should be strengthened, not just to improve our democracy, but to protect it against future threat.

"Electoral reform has been attempted by many, but achieved by very few.”