Rolling coverage of all today's political news as it happens
10.31am: My colleague Matthew Weaver is writing a WikiLeaks live blog which is covering the news of the arrest of the WikiLeaks founder Julian Assange.
10.15am: Ken Livingstone has named Val Shawcross as his running mate in the London mayoral contest in 2012. If Livingstone wins, Shawcross will be deputy mayor.
10.11am: Philip Davies, the Tory MP for Shipley, has been on Radio 5 Live to say that he has "concerns" about Kenneth Clarke's plans to cut the number of people in jail. "There is no reason why rehabilitation can't take place in prison," he said. According to PoliticsHome, he also said that David Cameron should not be making too many concessions to the Liberal Democrats.
We can't have the tail wagging the dog as far as the coalition is concerned. The Conservatives make up five-sixths or four-fifths of the coalition and you know, the prime minister ought to remember that he is also in coalition with the Conservatives.
10.10am: In the Commons this afternoon the European Union bill is going to get its second reading. This is the measure that says the government will have to hold a referendum if it plans to transfer any more power to the EU. On the BBC News this morning, William Hague, the foreign secretary, claimed this was "the most important piece of legislation on European matters since Britain joined the EEC as it was then in the early 1970s".
The bill also contains a "sovereignty clause", which makes it clear that EU law does not undermine the sovereignty of parliament. Today the European scrutiny committee has published a report explaining how this will work. The committee, which is chaired by Bill Cash, the Tory MP, says: "The evidence we received suggests that the legislative supremacy of parliament is not currently under threat from EU law."
9.39am: Earlier I said it would be interesting to see what Labour has to say about Kenneth Clarke's sentencing green paper. Judging by a comment released last night, the party is going to attack it on the grounds that it's a spending cut. This is statement issued by Sadiq Khan, the shadow justice secretary.
A sentencing review that should have been about reducing reoffending and protecting the public seems to have become just an exercise in cutting costs. Sadly, despite Cameron's rhetoric about putting the public first, the government have retreated to a traditionally Tory ideological approach, setting an arbitrary target for the prison population, rather than addressing the primary concern of protecting the public.
This suggests that we're in the curious position where a sentencing green paper that at face value appears rather liberal is getting more support from Michael Howard (see 8.47am) than from Labour. I'm sure the position will become clear in the Commons this afternoon.
9.19am: And here are the main points from Kenneth Clarke's interview with the Today programme. Some of the quotes are from PoliticsHome.
• He said that it was wrong to keep sending more people to prison. He mocked the idea that there was anyone who thought that having 85,000 people in prison wasn't enough. He also said that even in "the most rightwing states in the United States of America" the authorities had given up just trying to increase the prison population.
There has been a huge increase in the number of people in prison. It is not only not good value for money. Even more importantly, I don't think that is the right way to protect people.
• He claimed that it was not possible to prove a link between the number of people in prison and the crime rate. "You can't prove it one way or the other," Clarke said. "You could have charts [of some countries] where you get falling crime and it matches a falling prison population."
• He said the measures being announced today would cut the prison population by about 3,000.
• He said more rehabilitation was needed to stop a "criminal underclass" being nurtured in prisons. "We've got to stop having this revolving door where people go into prison, serve their time, come out and within less than a year half of them have committed some more crime," he said. He accused Labour of neglecting this issue.
The prison system at the moment is not doing one of the jobs it's meant to do, that is stopping developing a criminal underclass who just keep committing more crime as soon as they come out. That's because we're not tackling the problems of drugs, not tackling the problems of alcohol abuse, not tackling the problems of mental illness in prisons. We're not helping the ones that can go straight.
• He said that he expected Michael Howard to agree with everything he was announcing today. In jovial terms, he criticised the Today programme for trying to stir up a row between them.
8.47am: Michael Howard (now Lord Howard) was on the Today programme earlier this morning. Rather to the disappointment of the producers, I assume, he said that he expected he would agree with everything that Kenneth Clarke would be proposing today.
I warmly welcome [Clarke's] approach to rehabilitation and I hope I'm going to be able to agree with everything in the green paper.
But Howard did confirm that there was still one issue on which he and his former cabinet colleague didn't see eye to eye.
The one point where I do disagree with him is when he suggests that the remarkable fall in crime we have seen since 1993 has nothing to do with the rise in the prison population. We have seen a very significant increase in the prison population since 1993 and an almost halving in the rate of crime. These two things have gone together - they are connected.
8.18am: David Cameron is in Afghanistan this morning. He has just been holding a press conference in Kabul. My colleague Polly Curtis is travelling with him and this morning she's already filed a fresh story about his talks with the Afghan president, Hamid Karzai.
Back in London, the key event is going to come at 3.30pm, when Kenneth Clarke, the justice secretary, unveils his green paper on rehabilitation and sentencing. My colleague Alan Travis has already outlined many of the measures that the document will contain and Clarke has just given an interview about his plans to the Today programme. (I'll summarise what he said shortly.)
But the Commons statement should still be pretty interesting, partly because we'll find out how much opposition Clarke attracts from the Tory right (Travis says in his story that the green paper was delayed because Downing Street had "presentational concerns" about Clarke's plans) and partly because we might learn more about where Labour stands on this issue. At the moment it's still not particularly clear whether Labour is going to try outflanking Clarke on the right.
Otherwise, it's a patchy day. At some point the Home Office is going to make a statement about student visas. Alan Travis (busy man) says that up to 120,000 international students from outside the EU who come to Britain to take "below-degree-level" courses could be refused entry. Iain Duncan Smith is giving a speech on welfare reform at 11.45am. Nick Clegg is also meeting Lib Dem MPs to discuss tuition fees, but that will be taking place tonight, after I've closed for business.
Until then, I'll be covering all the breaking political news, as well as looking at the papers and bringing you the best politics from the web.