Tory leader David Cameron is being urged to sign up to a new ministerial code to ensure a government led by him is open and accountable to Parliament.
The party's democracy task force, led by former chancellor Ken Clarke, wants to see a return to "proper" Cabinet government if the Tories get power.
Mr Clarke said the Conservatives must end the "presidential" and "sofa-style" of Tony Blair's government.
The Tory priority must be to restore voters' trust in politics, he says.
TASK FORCE RECOMMENDATIONS
New ministerial code to clarify main responsibilities of the prime minister and secretaries of state
Legislation committee to scrutinise all proposed bills
Code of conduct for government publications and advertising campaigns
Independence for Office of National Statistics
Halve number of special advisors
Restore 'objectivity' of Civil Service
Parliamentary approval required before sending troops to war
Parliamentary approval required before ratification of treaties with financial, legal or territorial implications for UK
Mr Clarke, in an interim report, has recommended a more traditional type of government, where ministers have more power than unelected advisers.
The report, An End to Sofa Government, said that "the combination of an over-powerful premiership and the dominance of news management within policy-making have been very damaging to both effective and accountable government".
Mr Clarke's democracy task force called for ministers to be given access to papers ahead of Cabinet discussions so they can consult their officials and consider issues, rather than just nodding through decisions in other departments.
He said: "It is difficult to exaggerate how broken the system is at the moment."
He also said the civil service needed more independence, while decisions about going to war should be considered by Cabinet and Parliament.
"I hope the politics will not just be based on seeking tomorrow's headlines or based on focus groups, but actually will be based on some considered view...on what's best in the national interest," he told BBC Radio 4's Today programme.
A "new and strengthened" code should be approved by Parliament and monitored by a body with similar powers to the National Audit Office, the report recommended.
It also called for the number of political special advisers to be halved, with their role clearly defined as giving advice rather than giving directions to career civil servants.
This is the first report by the task force, which began work in 2005.
In a speech that year, Mr Clarke said: "A British 'presidency' has been created in Number 10.
"Too much power has been concentrated in the hands of the prime minister.
"We have seen a wholesale and deeply regrettable move from Cabinet government to autocratic government."