Labour would get an 8-point bump in the polls if Jeremy Corbyn was not the party's leader, according to a new poll.

The UK-wide BMG survey for The Herald highlights the scale of the electoral challenge facing Labour as Mr Corbyn prepares to give his first conference speech since his re-election.

But the poll also suggests that Mr Corbyn’s rival in the leadership election would not be doing any better.

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The result will come as a blow to the moderate wing of the party who had hoped that Owen Smith would transform their chances with voters.

Mr Corbyn will today (WED) set out plans for a new fund to funnel extra cash to areas of high migration.

But sources indicated that he was relaxed about migration levels, adding "it is not an objective to reduce the numbers, to reduce immigration".

Millions of Labour voters rejected the party's called to stay in the EU earlier this year, in part because of concerns about immigration.

Mr Corbyn will also tell his party conference to prepare for a General Election next year.

Labour is sceptical about Prime Minister Theresa May's pledge not to go to the country again until 2020.

Under the fixed-term rules Mrs May cannot call an election without Labour's help.

But a spokesman for Mr Corbyn last night said that Labour MPs would vote for another nationwide poll.

Labour are trailing Mrs May's Conservatives in the polls.

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BMG asked more than 2,000 people to consider whether they would vote Labour at a General Election under four different scenarios - a Corbyn-led party, a Smith-led party, a party where Corbyn has stepped down but the leader is unknown, and for good measure, an Ed Balls-led party.

They were asked the questions in a way that ensured that every order/combination showed up roughly an equal number of times.

They suggest that under Corbyn, Labour could attract up to 32 per cent of the vote, 11 per cent who said they would definitely vote for the party and 21 per cent who said that they would consider it.

Mr Smith as leader would make hardly any difference, with up just 1 point to 33 per cent.

Under the Welsh MP fewer voters, 7 per cent, said that they would definitely vote for the party while 26 per cent said that that they would consider it.

The data shows difference in the supporters of the two men, however.

Corbyn’s supporters tend to be younger than Smith’s.

Smith would have attracted more Liberal Democrats, and Corbyn more Greens.

But an unknown fresh face was the option that appealed most.

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Under that scenario 10 per cent said they would definitely vote for the party while 30 per cent would consider it, 7 percentage points higher than a party led by Smith, and 8 points higher than under Corbyn.

Finally, despite his recent high-profile appearance on Strictly Come Dancing, a Labour led by former shadow chancellor Ed Balls would be no less or more electable than under Corbyn or Smith, with potentially 32 per per cent of the vote.

Michael Turner, from BMG, said: "Now the Labour leadership campaign is over, the result of the latest BMG/Herald poll reveals that there would have been virtually no difference in the electability of the party at the next General Election under either contender."

Labour says that it does not comment on opinion polls.