Peter Mandelson the man with the power to appoint Prime Ministers and form governments?

What gives the twice disgraced, unelected peer, Peter Mandelson, the seeming right to decide who is Prime Minister and what parties form the government of the United Kingdom?

Rather like Charles Maurice de Talleyrand-Périgord he seems to subscribe to the mottoes:
'Regimes may fall and fail, but I do not.'
'We were given speech to hide our thoughts.'

So whilst the Conservative leadership sit around panicking, Peter Mandelson is engineering the end of Conservatism in the UK. Do remember that EU pensions are paid on the understanding that the EU can remove this pension, if in the view of the Commission or the Luxembourg Court, they "fail to uphold the interests of the European Communities", I wonder if allowing a Conservative government to be formed could be construed as failing to uphold the interests of the European Communities? As I asked in October 2008:

'1. If Peter Mandelson has to "uphold the interests of the European Communities" in order to receive his enormous EU pension then is he liable to act against the interests of the UK in order to safeguard his financial future?
2. If the above is true then why does the word treason come to my mind?
3. When will Peter Mandelson start to be in receipt of his EU pension?
4. If Peter Mandelson's pension starts to be paid as soon as he ceases to be an EU Commissioner then is his first loyalty, whilst Secretary of State, to the EU or the UK?
5. Is Peter Mandelson's pension at risk in the unlikely event of him standing up to the EU?
6. If his pension does not start paying out until he is 60 then is his pension at risk if he defies the EU between now and then? '