Referendum and fixed-term parliament bills expected
More details are expected of proposed changes to the voting system, cuts to the number of MPs and the plan for fixed-term parliaments.
The Cabinet Office will publish the two bills on Thursday, the BBC understands.
The bill paving the way for a referendum on changing the election system to the alternative vote is expected to include detail on how the question will be framed.
The second bill will be on fixed five-year term parliaments.
The referendum on changing the general election system from first past the post, is due to be held on 5 May 2011.
Under the plans for fixed-term parliaments the next election is set to be held on 7 May 2015.