• Conservatives in discussion with Liberal Democrats about idea of replacing act with British bill of rights • Nick Clegg warns government would 'tamper with act at its peril'

Theresa May, the new home secretary, today confirmed that the new coalition government is reconsidering the Conservative manifesto pledge to scrap the Human Rights Act.

She made the announcement as Nick Clegg, the Lib Dem deputy prime minister, said that any government would tamper with the HRA "at its peril".

The Liberal Democrats strongly criticised the Tory election policy on the HRA before the election and what to do about the act has been one of the biggest problems for the coalition. May said that the Conservatives were in discussion with the Lib Dems about what to do in this area and that this was an example of what the "new politics" was like.

The decision about whether to introduce a British bill of rights, supplanting the European convention on human rights, is to be passed to an independent commission. The news emerged prior to the publication of a full coalition agreement between the two parties tomorrow, replacing the seven-page agreement rushed out following weekend talks.

The Conservative party has been divided over whether to support a bill of rights, and whether it would interpret or supplant the European convention.

The Tory manifesto said: "We will replace the Human Rights Act with a UK bill of rights." But, this morning, when May was asked about the manifesto promise in an interview on BBC Radio 4's Today programme, she downplayed the significance of this pledge. "We did say that we thought the Human Rights Act was not working in certain areas," she said.

She went on: "We are currently in discussions with our coalition partners about what we will be doing in this area."

In an interview in the Times today, Clegg said: "Any government would tamper with [the HRA] at its peril."

The attorney general, Dominic Grieve, has strongly opposed British withdrawal from the ECHR, and was one of the few Tories to admit he had been "broadly comfortable" about its incorporation into UK statute law, which came through the Human Rights Act.

He said in a lecture last November: "There is a complacency among lawyers, academics and campaigners who support the Human Rights Act as to the extent of public resentment of the operation and influence of the legislation itself."

Grieve argued that a British bill should use the ECHR "as a starting point" but should be allowed to clarify these rights in greater detail, as well as its relationship to the Strasbourg courts that oversee the ECHR.

Clegg will today set the highest possible bar for his plans to reform politics when he claims the government's programme represents "the biggest shake-up of our democracy since 1832, when the Great Reform Act redrew the boundaries of British democracy, for the first time extending the franchise beyond the landed classes."

He will promise in his first speech as DPM: "This government is going to transform our politics so the state has far less control over you, and you have far more control over the state. I'm talking about the most significant programme of empowerment by a British government since the great enfranchisement of the 19th century."

Clegg will claim he is not offering incremental change but a wholesale, big-bang approach to political reform. He will promise abolition of the ID card scheme, the national identity register and second-generation biometric passports.

He risked angering some Tories when he told the Times the coalition would aim to make taxes fairer, rather than reduce the overall tax burden. Clegg was asked if he expected the government would reduce the overall tax burden. He replied: "No, I am saying we'll rebalance the tax system. We're not making great claims about the overall tax burden."

In his speech Clegg will also promise: "We won't hold your internet and email records when there is just no reason to do so. CCTV will be properly regulated, as will the DNA database, with restrictions on the storage of innocent people's DNA.

"And we will end practices that risk making Britain a place where our children grow up so used to their liberty being infringed that they accept it without question."

The ContactPoint database, designed to hold information on all children under 18, will be scrapped and schools "will not take children's fingerprints without even asking their parents' consent".

Clegg will promise to repeal restrictions on the right to protest, and review libel laws. He will also say he will ask the public to tell the government which of thousands of criminal offences should be repealed, saying taking away people's freedom has not made people safe.

The advance copy of the speech makes no mention of the Lib Dem plan that no one currently given a prison sentence of less than six months will actually go to jail.

Clegg will also promise a mechanism to block pointless new criminal offences, as pledged by the Lib Dems.

Clegg's plans to put liberty and political reform at the centre of government will be tested as he comes up against resistance from more authoritarian Tories in the Home Office, but he is likely to find broad support from the Ministry of Justice, run by Kenneth Clarke, the new lord chancellor, and his Lib Dem minister of state, Lord McNally, a veteran supporter of constitutional reform.

One test of Clegg's speech will be whether he sets out a timetable for Lords reform and for a referendum on the changes to the electoral system. He is likely to be asked if he has detailed plans to introduce reform of party political funding through new caps on donations, state aid and limits on spending during the electoral cycle.