Here are today's need-to-know political developments:

- Former Tory cabinet minister Lord Heseltine said David Cameron was "right" to renegotiate the issue of immigration with Europe but said he was "more likely to be successful" if he had the backing of the whole party

- Ex-International Development Secretary Owen Paterson urged the government to maintain the "purdah" period in the run-up to the EU referendum, warning that the result would be "illegitimate" if the public felt it had been "rigged"

- SNP MP Alex Salmond called on political parties in the Commons to join with the SNP to ensure the EU referendum cannot be held on the same day as devolved elections in Scotland, Wales and Northern Ireland 

- Former chief whip Andrew Mitchell said he didn't believe the government would be able to persuade Parliament to leave the European Convention on Human Rights

- Shadow chancellor Chris Leslie said all of Labour's policies were "up for review" after the election, and admitted that "with hindsight" the previous Labour government could have spent less and "braced ourselves" more for the 2008 financial crash

- George Osborne is to deputise for David Cameron at Prime Minister's Questions on Wednesday, facing shadow foreign secretary Hilary Benn across the despatch box.

Sky News

Image source, Getty Images

Chuka Umunna, Labour's shadow business secretary, has told the Murnaghan programme that the party should not campaign alongside the Conservatives for a Yes vote to remain in the EU.

It comes after reports a group of senior Labour frontbenchers is planning to set up an "unashamedly pro-European campaign group", following disagreements in the shadow cabinet over how to approach the EU referendum.

Campaigners have welcomed plans to fast-track through Parliament new laws aimed at sparing girls from female genital mutilation (FGM).

Under the plans, local authorities, social workers and police would be able to apply directly to courts to suspend passports and other travel documents of anyone suspected of trying to take someone abroad for FGM.

David Cameron told the Observer that the plans could go through Parliament in weeks:

The Daily Mail

Image source, AP

The Daily Mail reports, external that a study into the repair work needed at the Houses of Parliament will warn that it "could be destroyed without a £3bn repair job with MPs moved out for years". It says the report will be published next week.

The Grade I-listed building suffers from flooding, contains a great deal of asbestos and has fire safety issues.

Speaker John Bercow has warned that Parliament could have to be "abandoned" within 20 years unless a significant restoration is undertaken.

Sky News

Asked whether the UK needs a new Magna Carta, Jacob Rees-Mogg says a British Bill of Rights - which the Conservatives want to introduce - as a new Magna Carta is "a very attractive idea".

Sky News

Monday sees the 800th anniversary of the sealing of Magna Carta. Conservative MP Jacob Rees-Mogg says the document is "tremendously important" as it says "the king is under the law rather than the king is the law", which is "the basis of all our freedoms".

The Queen, David Cameron and Prince William will join thousands of invited guests to mark the anniversary tomorrow.

Mr Corbyn, 66, said he wasn't looking for "personal aggrandisement" by standing for the Labour leadership, as "I'm much too old for that kind of thing".

Andy Burnham, Yvette Cooper and Liz Kendall are the other three candidates vying for the top job. Mary Creagh pulled out of the race on Friday.

Labour leadership hopeful Jeremy Corbyn was on Sky News' Murnaghan programmer a little earlier. He said he had secured the backing of 22 MPs, which is 13 short of the 35 needed to get on the official ballot before nominations shut on Monday.

The Islington North MP, who is standing on a left-wing ticket, said he wanted to raise the "Labour tradition" of public enterprise, public ownership, investment in social and health services.

Tom Newton Dunn predicts George Osborne will announce some interesting new government policy at PMQs, "because he can".

"He will take every single opportunity between now and whenever the [Conservative leadership contest] begins, next year or in four years' time, to do just that."

David Cameron has said he will not seek a third term as prime minister, leading to speculation over who his successor will be.

George Osborne will host prime minister's questions on Wednesday as the PM is away on official business. Shadow foreign secretary Hilary Benn will face him across the despatch box for Labour.

Janan Ganesh says William Hague - who stood down at the election - used to deputise for the PM and was widely regarded as one of the best Commons performers. And George Osborne used to write his jokes, he adds, so that's "one thing he's got going for him".

The Sunday Politics panel is discussing reports that UK intelligence agents have been moved because Russia and China have access to classified information which reveals how they operate.

According to the  Sunday Times, external , Moscow and Beijing have deciphered documents stolen by whistleblower Edward Snowden.

"There's no doubt Snowden did enormous amounts of damage," says The Sun's political editor Tom Newton Dunn. But Polly Toynbee says it was a price worth paying.

Political commentator Janan Ganesh says it's impressive that Yvette Cooper is so close behind Andy Burnham (who currently has the most nominations) and predicts she'll hoover up a lot of second preference votes. She could come through as the "least offensive candidate, the vanilla option".  

Parliamentary Labour Party nominations for the Labour leadership close on Monday. Will it be a four-person race? "Difficult to tell," says Guardian columnist Polly Toynbee. But she says that if you have one outsider - like Jeremy Corbyn - who is free to say whatever he likes, "it makes the others sound stiffer".

The Sun's Tom Newton Dunn thinks gender will come into play, with people in the party saying at least one of the top jobs has to go to a women.

Conservative MP Mark Field is asked about Zac Goldsmith's candidacy for London mayor, and whether it will cause a problem for him that he ruled out standing for so long before changing his mind.

Boris Johnson did more or less the same, he quips. He described Mr Goldsmith, Richmond Park MP, as "a bit of a maverick" in the competition, and says there is "a sense he appeals beyond the traditional Conservative family".

Put to him that Sadiq Khan may be seen as too close to the Ed Miliband era, Ken Livingstone says Mr Miliband's leadership did the party "no harm" in London, saying he went down "very well" in the capital.

He says he thinks Sadiq Khan understands the problems facing ordinary Londoners "very well".

None of the six Labour candidates "would be a bad mayor", says ex-London mayor Ken Livingstone. He says he's supporting Sadiq Khan because he's "like me, a rather nerdy, working class boy who likes to run things". But he restates that he's not opposed to any of the others in the running.

"We are part of the EU... and if our voice is not being heard loud enough, then that is our responsibility," says Laura Sandys.

Philip Davies says the PM can set as many targets as he likes on migration "but there is nothing he can do" to stop people coming to the UK, saying the current levels of  migration are unsustainable. 

Laura Sandys says she doesn't dispute migration is an issue, "but coming out of the EU, or this twilight position, isn't going to help it".

"The EU will not allow us to have access to the single market without free movement of labour," she says - a point contested by Mr Davies.