Nick Clegg has published the bill designed to introduce an elected House of Lords as Downing Street warned potential Tory rebels that they would be making an "interesting career choice" if they rebelled against the plans.
The House of Lords Reform Bill sets out plans to replace the current unelected House with an 80% elected 450-member chamber.
Under the plans outlined on Wednesday, members of the reformed House would serve for 15-year terms of office and they would only be allowed to serve for one term.
In a statement issued alongside the publication of the Bill, Clegg said the coalition stood "on the brink of an historic achievement".
"After more than a hundred years of debates, cross-party talks, Green Papers, White Papers, Command Papers and a Royal Commission, we are finally introducing a Bill to create a democratic and legitimate House of Lords.
“It cannot be right that ordinary, hard working people are expected to obey laws that are created by people appointed entirely by birth or patronage, who have a generous pay packet and a job for life. The time for idle talk is finished. Now is the time for action.”
However the deputy prime minister has a battle on his hands to push the legislation through, as it faces fierce opposition from as many as 100 Tory MPs as well as a large number of peers from all parties.
Among the Tories who oppose the Bill is Conor Burns, who is believed to be planning to resign from his job as a parliamentary private secretary (PPS) to Northern Ireland secretary Owen Paterson.
Speaking on BBC Radio 4's Today programme this morning, Burns said: "If I lose my job for something that was a mainstream view within the Conservative party within the last parliament, which serving cabinet ministers held as their view, so be it."
Speaking after prime minister's questions on Wednesday, a Downing Street spokesperson said PPS' or ministers who voted against the Lords bill would be sacked and would have made an "interesting career move" - suggesting they would not be quickly forgiven.
David Cameron told MPs they had "been discussing this issue for 100 years" and that it "really is time to make progress".
"There is a majority in this House for an elected House of Lords and I believe there is a majority for that in the country," he said.
He also took a swipe at Labour, warning them not to play political games with the Bill. "If those who support reform don't get out there and back it, it won’t happen," he said.
While Labour has said it supports reform, the party looks set to attempt to derail the timetable for pushing it through.
Ed Miliband wants more days allotted to debating the legislation, and the party has confirmed it will join with Conservative rebels to vote down a motion setting out its passage through parliament.
Ministers aim to make the Bill law by the spring but a defeat on the timetable would pave the way for as much as four or five weeks of debate in the autumn, which would swallow up time needed by for other business.
Labour is expected to table an amendment demanding that any change is subject to a national referendum - something that the Government has firmly ruled out.
A date for the opening debate - and a crunch vote on the timetable for its progress - will be announced by Commons Leader Sir George Young on Thursday.
It will be held before MPs depart for their summer recess on 17 July.
Many of the critics of the plans are worried that an elected House of Lords would challenge the supremacy of the House of Commons.
At present the Parliament Acts give the Commons the power to overrule any objections the Lords make to legislation if they so wish.
The government has insisted that the reformed House of Lords would not challenge the historical primacy of the House of Commons as the new Bill specifically states that the Parliament Acts of 1911 and 1949, which define the relationship between the Houses, remain in force.
However opponents of the Lords reform worry that once members of the Lords are elected they will no longer see it as legitimate for MPs to be supreme, as the basis for the Parliament Acts was that the elected House should have primacy.
Tory MP Jessie Norman told BBC Radio 4's World At One that the concessions were "completely inadequate to the task set."
And he said the bill was a "constitutional monstrosity" and that would vote against it "absolutely without any question whatsoever".