Conservatives must be prepared for increasing unpopularity as the spending cuts begin to affect public services, party activists have been warned.

Health secretary Andrew Lansley warned of the anger the government is likely to face from voters as a result of the “difficult decisions” it is taking to cut the deficit.

He predicted the political landscape over the coming months will continue to be dominated by this month’s comprehensive spending review, in which George Osborne will outline plans for most Whitehall departments to make cuts of around 25%.

Speaking at a fringe event at the Conservative Party conference in Birmingham, Mr Lansley said the government will also be judged by its performance on public service reform and if it can make a “real difference”.

He also praised Prime Minister David Cameron, who he said had “personally” led a change in the attitudes of the party, particularly on social issues.

Explaining the fact that Tory popularity waned and then came back at different points between 1979 and 1997, Mr Lansley said: “The essence of that was that the Conservative Party in government was not aiming to be popular all the time. What we were aiming to do was to do the things that needed to be done so that at the subsequent election people would recognise that a Conservative government had succeeded and a Conservative government should be re-elected.

“I think, frankly, that is the position we are in. We will not be popular. We must expect not to be popular because, much as we know that the nature of the difficult decisions that we have to do are in that sense of our making, we didn’t create the debt crisis.”

He added: “The public accept we do need to deal with the deficit … if we are pondering what the political landscape looks like this autumn it is all about the spending review and the consequences of the spending review. We must brace ourselves for that.”