Updated

LONDON (AP) — Deputy Prime Minister Nick Clegg on Monday outlined plans for a sweeping shake up of Britain's political system, one that could nudge the U.K. from a mainly two-party system toward more European-style coalition politics.

Clegg told lawmakers that he wants to hold a referendum on a new voting system, prune the number of lawmakers from 650 to 600, and redraw the boundaries of Britain's parliamentary constituencies.

If enacted, the changes could be among the biggest reforms to Britain's parliamentary system since British women won the vote in 1918, or the voting age dropped from 21 to 18 in the mid-1960s.

Clegg said that changes would "restore people's faith in their politics once again," but the leader may have difficulty getting what his party most desires: A change from Britain's "first-past-the-post" electoral system, in which the candidate with the most votes wins, even if he or she garners less than 50 percent of the total.

The current system tends to favor Britain's two largest parties — the Conservatives and Labour — and has long locked Clegg's third-place Liberal Democrats out of power.

The new system, known here as alternative voting, would allow voters to rank candidates in order of preference, with second or third choice votes allocated if no candidate wins 50 percent of the first preference votes. Liberal Democrats hope the new system will translate into more seats — and a more permanent place at the center of the British political establishment.

But Prime Minister David Cameron, the Tory leader and Clegg's senior partner in the two party coalition now running the country, opposes the change. Cameron only agreed to the referendum as part of a deal to get the Lib Dems to join his government after he failed to take a majority in the May election, and has vowed to campaign against it when it's put to voters.

Some within the opposition Labour Party also have expressed reservations.

Nevertheless, the Tories do plan to back the reorganization of Britain's constituencies and the trimming of the number of lawmakers by nearly 10 percent. All three of Britain's biggest parties were stung by revelations last year that lawmakers had charged the taxpayer for everything from duck ponds to moat clearing, and the issue focused attention on the unusually large number of parliamentarians serving in the U.K.

Clegg also said the government would effectively give up the right to call elections at will, by requiring a two-thirds majority of all lawmakers to dissolve parliament. Under the current system, a simple majority is all that is required to call an election, a rule which can easily tempt those in power to spring an election on their opponents whenever their poll ratings are at the highest.

However, a majority vote of no confidence will still be able to topple a government.

"It simply is not right that general elections can be called according to a prime minister's whims," Clegg said. "So this prime minister will be the first prime minister to give up that right."

Clegg said that "these are big, fundamental reforms we are proposing," but he argued that British voters had endorsed his call for reform.

Labour lawmaker Jack Straw complained that some of the changes were arbitrary and potentially damaging.

Clegg's referendum is due to take place on May 5, 2011. If the changes are approved, the new rules would be in place ahead of Britain's next general election, in May 2015.