Senior Labour figures have begun openly to express fears over the "corrosive" effects of cash-for-honours allegations after Tony Blair was questioned by police for a second time.
Party chairman Hazel Blears said the inquiry was damaging the Government's ability to communicate with voters and justice minister Harriet Harman said trust had been "eroded".
They both spoke out after ex-leader Neil Kinnock said it will take "years" for the reputation of the political system to recover.
Ms Blears - tipped as a contender to be the party's next deputy leader - said: "Inevitably, when you have this kind of thing going on for months and months, it does have a corrosive effect.
"It is damaging for politics because there is a corrosive cynicism around that I think is damaging for the country," she said.
"This whole affair has overshadowed our domestic agenda: it is quite difficult to get your message across. I want the investigation to be brought to a conclusion as quickly as possible."
Ms Harman - a declared candidate in the race to succeed John Prescott - said: "It has eroded trust and it's been an unfortunate, to say the least, situation."
It emerged on Thursday that the Prime Minister was quizzed last Friday at Downing Street by detectives investigating allegations of the sale of honours.
But the interrogation was kept secret as police asked for a news blackout for so far unexplained "operational reasons".
Scotland Yard said Mr Blair was questioned as a witness "to clarify points emerging from the ongoing investigation", but declined to go into further detail.
