Gordon Brown was facing a backlash over his decision to leave an unelected peer running the country during his holiday, according to a poll.
Despite Labour enjoying its best spell for months under Lord Mandelson's watch, 67% of voters thought he should not have taken the reigns.
Just 16% approved of the Business Secretary acting as a stand-in, research for The Sunday Times found.
However, there was better news for the peer in a separate poll which suggested his performance had boosted his popularity among Labour supporters.
A survey by ICM for the Sunday Mirror indicated 21% would back him as a successor to Mr Brown - making him second favourite behind Foreign Secretary David Miliband.
The YouGov/Sunday Times research also revealed widespread public gloom over the country's economic prospects.
Some 69% reckoned the economy would not start recovering until at least next year, with just 7% saying it was already back in growth.
After unemployment climbed to 2.4 million this week, almost 45% of people expressed fear that they or a close member of their family would lose their job as a result of the downturn.
Overall, Labour's support stood slightly higher than last month at 28%, 14 points behind the Conservatives who were unchanged on 42%. The Liberal Democrats were on 18%.
Meanwhile, the Sunday Mirror poll put the Tories up two on 43%, Labour down one on 26% and the Lib Dems on 19%.
