Just 45% of Labour supporters back Jeremy Corbyn as the best prime minister for the country in a head-to-head choice between him and Theresa May, according to a new poll.
Among all voters, support for Mr Corbyn entering Downing Street slumps to 14%, with Mrs May given the nod by 47% in a two-way contest, an Opinium survey for The Observer finds.
The poll shows the general Tory lead over Labour falling to nine points, with the Conservatives down 3% to 38%, and Mr Corbyn's party up one to 29%, with Ukip on 14% and the Liberal Democrats on 7%.
This is in marked contrast to a separate ComRes poll for the Independent and Sunday Mirror that shows the Tories powering 21% ahead of Labour.
The Conservatives are up four points to 46%, while Labour remain unchanged on 25%, with the Lib Dems on 11%, and Ukip on 9%, according to the ComRes survey.
The findings come as Mr Corbyn faces renewed attacks on his leadership ahead of next month's local elections after Labour lost a Middlesbrough council seat to the Tories in recent days on a by-election swing of 8%.
Labour MP for Middlesbrough South and East Cleveland Tom Blenkinsop, a strong critic of Mr Corbyn, said: "We lost due to the leader's name being mentioned on the doorstep as the reason why residents were not voting Labour."
When asked which party was most trusted to lead Brexit negotiations, 35% backed the Conservatives, the same as last month, while Labour's rating stayed static on 12%, The Observer poll said.
Health and Brexit remained the most important issues among voters, but terrorism climbed from fifth to third place in the aftermath of the attack at Westminster.
Labour, on 28%, enjoys an eight-point lead over the Tories when it comes to the NHS, but Mr Corbyn's party was named by just 7% as having the best policies on immigration - the fourth most important issue to those questioned.
The ComRes poll found that President Donald Trump's missile strikes on Syria were backed by 38%, and opposed by 35%.
Asked whether Foreign Secretary Boris Johnson was a hindrance to the Government's foreign policy objectives, 37% said yes, and 32% said no.
:: Opinium Research carried out an online survey of 2,002 UK adults aged 18 and over from April 11-13 2017. Results have been weighted to representative criteria.
ComRes interviewed 2,029 adults online from April 11-13 with data weighted to be demographically representative of all British adults. Data were also weighted by past vote recall.