Theresa May's rating has plunged to the worst on record for a prime minister in the weeks after an election, according to pollsters.
Labour is also one point ahead in the polls on 42% compared with 41% for the Conservatives, Ipsos Mori found.
After riding on a historic high at the start of the general election campaign, the PM has hit an unprecedented low.
But while opponent Jeremy Corbyn's rating continues to improve, Mrs May is still regarded as the most capable premier.
The study found 34% of voters said they were satisfied with the Prime Minister's performance, down nine points from last month and 22 points from April, when she called the election.
Some 59% are dissatisfied with Mrs May, leaving her overall rating on minus 25, the worst score Ipsos Mori has recorded for a prime minister in the month after a general election.
Mr Corbyn's ratings were up five points from June with 44% satisfied while 45% were dissatisfied leaving the Labour leader with a net satisfaction score of minus one.
Asked who was more capable of being prime minister, 46% of voters went for Mrs May compared to 38% for Mr Corbyn.
Gideon Skinner, head of political research at Ipsos Mori, said: "The turnaround in Theresa May's ratings is unprecedented in our previous data on prime ministers, from a historic high at the start of the campaign to a historic low just one month after an election, while also seeing her position among her own party supporters weakening and Jeremy Corbyn's campaign surge continuing.
"Having said that, she still has the edge as most capable PM among over 35s."