The Chief Secretary to the Treasury is assiduous at keeping in touch with Conservative backbenchers, according to his colleagues, and he knows he will have to secure their support for the tough round of public spending cuts which he is preparing.
While some may have questioned the wisdom of Mr Portillo's speech on Wednesday, which set alarm bells ringing about imposing prescription charges on children and the elderly, it was intended to prepare the ground for tough decisions ahead.
A founder member of the No Turning Back group of Thatcherite MPs, Mr Portillo mixes his right-wing ideology with a sound dose of pragmatism. However, those close to him detect no watering down of his Thatcherite views.
'The interesting thing about Michael is that people thought he would trim and drift to the centre, but he hasn't done that. He is just as right wing as he always was,' said one Whitehall insider.
Mr Portillo's first high-profile appointment under Margaret Thatcher was to prop up the failing reputation of the poll tax. When that failed, he continued to fight for some element of the poll tax to be retained in the council tax.
'Everyone else wanted to cut off its head, stick in the garlic and shove a stake through its heart, but Michael defended it to the last,' a ministerial source said.
The son of a republican who fled Spain, Mr Portillo, who got a first at Peterhouse, Cambridge, was a contemporary of Bruce Anderson, the journalist, at the Conservative research department, and was an aide to Nigel Lawson at the Treasury before winning the Enfield by-election after the murder of Sir Anthony Berry in the Brighton bombing in 1984.
When Lady Thatcher was faced with a vote of no confidence from her own Cabinet, Mr Portillo was a member of a No Turning Back delegation who tried to speak to her to stop her from resigning.
In recent weeks, as rumours of the impending reshuffle have gained momentum, Mr Portillo has been mentioned by many Tory MPs as a prime candidate for promotion. He is a long-term favourite, one day, to replace Mr Major.
His friends believe he should now be given the wider experience of his own department. But colleagues say that his star is linked to Norman Lamont at the Treasury. 'If Norman goes, Major couldn't move Michael. He needs some continuity at the Treasury.'