Conservative leader David Cameron has called for curbs on prime ministers' power to declare war or agree treaties without the approval of MPs.
Mr Cameron wants MPs to have greater input in key areas
Mr Cameron wants his party's democracy task force, headed by ex-Chancellor Ken Clarke, to examine the way ministers use the Royal Prerogatives.
He wants more key decisions to be down to MPs, rather than the prime minister.
Last year Gordon Brown called for a debate on whether MPs should have the final say on sending troops to war.
The Royal Prerogatives are a series of historic powers officially held by the Queen that have, in reality, been passed to politicians.
They enable decisions to be taken without the backing of, or consultation with, Parliament.
Mr Cameron has explicitly ruled out any change to the Queen's personal prerogative powers, such as the power to dissolve Parliament and appoint the prime minister.
But in a speech in London on Monday, he said trust in politics could only be restored if MPs, rather than the prime minister, had the final say over whether troops were committed to military action.
Lord Butler appointed
He said: "The prime minister is able to do what he wants without consulting Parliament at all.
"In the case of the Iraq war, there was a vote - as there was under John Major as well - but there are no formal arrangements on when that vote should take place.
"In Kosovo there was no vote at all."
Mr Cameron said it would still be possible to send troops into action urgently without having suddenly to assemble Parliament.
He also wants MPs to be given a formal role in areas including making international treaties and changing the structure of government.
And he suggested holding "parliamentary confirmation hearings" for major public appointments, such as the BBC chairman or the chief executive of the NHS.
But the new democracy task force will not look at introducing proportional representation to British elections.
Ex-Cabinet secretary Lord Butler, who investigated the intelligence-based origins of the Iraq war, is being appointed to the task force.
Lord Butler has been critical of Tony Blair's "sofa style" of government, saying the Cabinet had been bypassed in favour of small, informal groups of advisers to help him make decisions.
In December, Chancellor Gordon Brown argued that limits on government power were an important part of the British tradition of liberty.
There was "a case for detailed consideration of the role of Parliament in the declaration of peace and war", he said.
Ex-minister Mr Clarke told BBC Radio 4's Today programme there needed to be checks in place to stop "personal, arbitrary, presidential rule".
But Northern Ireland Secretary Peter Hain pointed to major constitutional changes made in recent years, including the Human Rights Act, devolution and reform of the House of Lords.
"The Tories are very belatedly, having opposed every one of these changes and reforms in recent years, starting to catch up with Labour in wanting a modern, viable constitution with more accountability and more democracy," he told Today.
Campaign group Charter88 welcomed Mr Cameron's pledge but urged the Tories to back their calls for a written constitution to show where power lies in Britain.