David Cameron faces a grilling at the Leveson Inquiry over the nature of his close relations with senior newspaper executives on Thursday.
It is likely that his examination under oath at the Royal Courts of Justice will centre on issues such as the appointment of Andy Coulson as Downing Street spin chief and his friendship with Rebekah Brooks.
The Prime Minister will set out tighter controls on special advisers and ministers overseeing media takeovers amid continued pressure for an inquiry into Culture Secretary Jeremy Hunt.
Coulson's and Brooks' appearances at the inquiry threw up a series of questions over Mr Cameron's own actions both as opposition leader and after he entered 10 Downing Street in 2010.
The Prime Minister has conceded that he was guilty, just as his predecessors were, of getting too close to media proprietors and has called for relations to be "reset".
He has strongly denied doing any deal with Rupert Murdoch's media empire in return for the pre-election support of The Sun newspaper or helping approve his bid to take over BSkyB.
Details of a string of meetings with the media mogul and other senior figures before and after the 2010 election will be probed however.
Mr Coulson, recruited by Mr Cameron after resigning as News of the World editor over the initial phone hacking convictions in 2007, disclosed in his testimony that the PM did not press him for more details after July 2009, despite a stream of disclosures indicating the problem went deeper.
Meanwhile former News International boss Mrs Brooks laid bare the closeness of her friendship with the Tory politician - including his habit of signing off texts "lol" apparently in the belief it meant "lots of love".
He sent a message urging her to "keep your head up" when she too resigned over the phone hacking scandal and expressed regret that he could not be more loyal, she disclosed.
And she also set out a series of meetings with him following the election, including a Christmas dinner party at the Brooks' Oxfordshire home on December 23.
The prime minister is reported to have spent a significant amount of time preparing for his appearance before the inquiry.
The Daily Mail reports that Andrew Feldman, the Cameron's friend from university and the co-chairman of the Tory Party has been playing the role of Leveson QC Robert Jay in practise sessions.
Mr Cameron has admitted that while there he discussed News Corporation's takeover bid for BSkyB with James Murdoch while the Government was deciding whether to approve it.
His decision to give Mr Hunt quasi-judicial responsibility for that bid, despite being aware of his party colleague's sympathy with News Corp's case has proved highly controversial.
Documents submitted to the Leveson Inquiry disclosed that Mr Hunt sent a memo to the Prime Minister before he was put in charge warning against referring it to a regulator.
The Culture Secretary took charge after Business Secretary Vince Cable was recorded telling undercover reporters that he had "declared war" on Mr Murdoch - creating a perception of bias.
Labour, which last night failed to secure a Commons majority for Mr Hunt to be investigated over alleged breaches of the ministerial code, say the issue calls into question Mr Cameron's judgment.
The vote was comfortably won by Tory MPs despite the abstention of their Lib Dem coalition partners on the direct orders of Deputy Prime Minister Nick Clegg who favours an inquiry.
Mr Cameron insisted his adviser on the code, Sir Alex Allan, had told him he could not "usefully add to the facts" in the Hunt case uncovered by the Leveson Inquiry.
He has informed Sir Alex of plans, to be detailed today, to extend the code to cover the conduct of special advisers and the exercise of quasi-judicial responsibilities.
Downing Street said Mr Cameron had been receiving advice from a QC and the Treasury solicitor as he prepared to give evidence.