Brexit anxiety is fast becoming a theme in the UK as the two-year-long talks with the EU continue, a Survation survey showed on Tuesday 4 July.
The telephone poll, of more than 1,000 people between 28 and 30 June, found that 49% of respondents were not confident that the Conservative government would secure a good deal from Brussels once negotiations are completed around 2019.
That is compared to 38% of voters who were confident that Theresa May and Brexit Secretary David Davis would broker a good agreement with the EU, whilst 13% of respondents said they did not know.
"'Brexit Anxiety' has been a theme of recent polling on the topic and a lack of confidence in whether the government will secure a good deal for Britain is apparent," Survation said.
The research also revealed that the public want a formal role for the devolved governments of the UK, including Northern Ireland, Wales and Scotland, in the Brexit negotiations, with 61% of respondents backing the proposal, 32% of voters opposing it and 7% of people saying they did not know.
Elsewhere, the poll found that Jeremy Corbyn reached a new high in the 'best prime minister' rating with 38%, but the Labour leader was still six points behind May on 44%, with 19% of respondents selecting do not know.
"Labour's leader has almost doubled his public rating on this measure since we begun this question series in early May, when Survation were recording a significant Conservative lead over Labour," Survation said.
"May's popularity has fallen six points since the general election, using the same telephone methodology that correctly indicated a Conservative victory with no overall majority."
The survey comes almost a month after May's plan to bolster her pro-Brexit mandate by holding a snap general election backfired, with the Conservatives losing their majority of MPs in the House of Commons.
The prime minister has since secured a so called "confidence and supply" deal with Northern Ireland's Democratic Unionist Party (DUP) in a bid to pass legislation and continue to govern with a minority government.
May has promised to quit the EU's single-market and customs union so that Britain can introduce tougher immigration rules and broker its own free trade arrangements with non-EU nations.
But the prime minister's cabinet seem to be split over a potential post-Brexit transitional deal, which would see tariff-free trade between the UK and EU nations temporarily maintained.
Chancellor Philip Hammond, a Remain campaigner, supports such a move in a bid to avoid a "cliff edge" for British businesses, but Brexit Secretary David Davis said that the UK will leave the EU's customs union and single-market by March 2019.