The public has little trust in politicians and people want MPs to tell the truth, says a standards watchdog.
People say they want politicians to show more honesty
The Committee on Standards in Public Life said a significant number felt the Iraq war affected trust, but fewer cited this factor than two years ago.
Chairman Sir Alistair Graham said public trust levels were at a "worryingly low level".
The survey also suggested people wanted politicians to own up to mistakes, and explain their reasons for decisions.
Less than one in four people (23%) trusted ministers to tell the truth and just one in three (29%) trusted the truthfulness of MPs in general.
This compared to a 93% trust rating for family doctors and 84% for head teachers.
Sir Alistair told BBC Radio 4's Today programme: "I don't think there has been a significant change but it is still staying at a worryingly low level."
On possible reasons for the lack of trust from the public, he said: "A significant number still say Iraq but it's significantly down from two years ago."
He also said people were "very clear" about what they wanted from the politicians they elected.
"They want politicians - and I don't think we should concentrate on [Tony] Blair, I think we should look at the whole political class as a whole - to own up when they make mistakes, explain their reasons more than they currently do for their actions and decisions.
"They very strongly want them to tell the truth and react strongly if they feel they are not.
"They also want them to be more in touch with what the public think is important."
Sir Alistair said he had discussed the survey's findings with Chancellor Gordon Brown over two meetings.
"He said that restoring trust between people and politicians was an absolutely critical issue and we will see if he follows that through," Sir Alistair said.
He later added: "What is needed is a sea-change among politicians of all parties in how political business, political debate and indeed how government is conducted."
Liberal Democrat front bencher Simon Hughes told the BBC most MPs were "honest and truthful" but that the actions of a few could spoil this image.
He said: "If every poster at a general election produced by a political party had to have been cleared by the Advertising Standards Authority - or the ASA would have the right to fine parties if they were not decent, honest and truthful - then there would be some discipline.
"But there are some very good politicians who do extremely good work, who are honest and truthful. And I think it is the few spoiling it for the many, not the other way round."
Labour MP for Birkenhead, Frank Field, said while politicians "don't come out very well as a collection of people", individual politicians often fared better.
"If the question in the survey is asked 'But what do you think of your local MP?' many more of us actually get some bonus points compared with us collectively," he said.
The survey of 2,000 people was conducted for the committee by Ipsos MORI in April.