Details of the coalition deal struck between the Tories and the Lib Dems are to be published in full, which the parties say is a "historic document".
In the foreword, David Cameron and Nick Clegg say although their parties have differences, there is "common ground".
But there may be tension as MPs learn which policies have been scrapped.
Conservative MP Bill Cash has said there is "very acute" concern among his colleagues that the Tory manifesto is being watered down.
The 30-page document was discussed by Lib Dem MPs at a meeting on Wednesday – a spokesman told the BBC "people were very pleased with the agreement".
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Prime Minister Mr Cameron and Deputy PM Mr Clegg will unveil the final document later – which will give more details than the four-page deal produced during negotiations in the days after the UK election resulted in a hung Parliament.
The Guardian reported that the two parties had agreed to try to privatise Royal Mail – an issue that proved explosive for the previous Labour government, which shelved it in the face of backbench and union anger.
In their manifesto, the Lib Dems proposed selling 49% to raise money for investment and splitting the remaining 51% between an employee trust and the government.
A spokeswoman for Business Secretary Vince Cable told the BBC: "All options that have been considered are consistent with the coalition agreement and details will follow".
The coalition deal includes the agreements worked out with civil servants on policy areas like banking, civil liberties, defence, the environment, Europe, immigration, welfare and political reform – some of which the parties have disagreed in the past.
But Mr Cameron and Mr Clegg, hailing the deal as a "historic document in British politics", wrote: "As our parties have worked together it has become increasingly clear to us that, though there are differences, there is also common ground."
The joint foreword promises "sweeping reform of welfare, taxes and most of all our schools – with a breaking open of the state monopoly and extra money following the poorest pupils".
BBC political editor Nick Robinson said the reference to schools was designed to reassure Tory activists and backbench MPs, some of whom viewed compromises between the two parties as a betrayal of manifesto commitments.
Mr Cameron risked stoking Tory backbench anger further on Wednesday evening when he unexpectedly asked his MPs to vote through changes to the powerful backbench 1922 Committee, which would allow ministers to play a bigger role – including voting for the chairman.
Mr Cash, who was also annoyed that the Tory commitment to replace the Human Rights Act with a "British Bill of Rights" has been referred to a government commission, told the BBC there was a "tsunami of changes taking place" which could "create a great deal of uncertainty and tension".
He said there was "very acute" concern among Conservatives that the party’s position was being watered down.
"We want things to work, we want stability, but there are also these democratic questions about being elected on manifesto commitments."
Pre-released extracts from the agreement on education show the parties have agreed on a "significant premium for disadvantaged pupils" as well as the Tory policy of allowing parents and charities to set up new schools.
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