An influential centre-left think-tank has warned that the UK's opposition Labour party has no chance of winning a majority in the next general election, which is scheduled to be held in 2020.

The report published on Tuesday by the Fabian Society, which is closely associated with Labour, said the party could at best hope for a coalition with other left-leaning parties.

Supporters of Labour leader Jeremy Corbyn had succeeded in winning "internal battles" but have made little progress in winning back lost voters, the think-tank said.

Corbyn's Labour was criticised for its "quietude, passivity and resignation" and its purportedly confused response to Brexit, in the report, titled "Apocalypse Soon?"

"On Brexit, the greatest political question for two generations, the party's position is muffled and inconsistent," wrote Andrew Harrop, the general secretary of the society, in a blog post accompanying the report.

"This is the calm of stalemate, of insignificance, even of looming death," he added.

READ MORE: The roots of Jeremy Corbyn's success

Labour currently holds 232 seats in parliament, with one up for by-election after an MP resignation, but the number could fall to as low as 140 if current trends persist, the report warned.

A total collapse of seats in England, similar to the near wipeout in Scotland in 2015, was unlikely due to the UK's first-past-the-post electoral system and the way likely Labour voters are concentrated in certain areas, the report said.

The Fabian Society is one of the UK's oldest left-wing think-tanks, with many senior Labour leaders having come through its ranks, including former prime minister Tony Blair, who has been a divisive figure within the party.

'Poor communicator'

Since his election as leader, Corbyn has faced a leadership challenge and has failed to secure the support of many of his MPs, who have publicly broken ranks with him over issues like Brexit, nuclear weapons, and military intervention.

However, the party's problems go beyond Corbyn, according to Oxford Brookes University academic Glen O'Hara.

"This is not a Left-Right issue, but about an instinctive feeling for the country's 'core'," O'Hara said.

"Corbyn himself, though a very poor communicator … makes this much worse, but the problem was there before him and will be there after him.

"(Labour) thinks, speaks and feels - and thus seems - nothing like how voters think, speak and feel themselves."

O'Hara also cast doubt on the effect that building electoral alliances with other parties would have.

Smaller parties like the Greens and the Welsh nationalist Plaid Cymru could only deliver a few seats, and the Scottish National Party (SNP) has little incentive in building an alliance with the party given its success in 2015, he said.

"An alliance with the Liberal Democrats might work better, but British voters don't and won't like the idea that elections are being 'stitched up' - decided behind closed doors - and might react against being told who to vote for."

A new leader and a coherent stance on Brexit could help the party, but the large pro-Corbyn base within Labour and a potential backlash from Eurosceptics over the latter would make each difficult, according to O'Hara.

For Corbyn's supporters, Labour's poor poll numbers were less to do with its leader and more to do with negative media coverage of the man and lack of support from his own MPs.

Many expressed anger at the British tabloids for their attacks on Corbyn after the report was published.

When Murdoch media & right wing biased press go all out to discredit #Corbyn you know you're backing the right man #Corbynfightback #Labour — Daniel Blake (@Jobaker46) January 3, 2017

Next election

Prime Minister Theresa May's Conservative party currently has a 15 point lead over Labour, according to pollsters, YouGov.

May has ruled out an election before 2020 but currently only has a slim majority of 14.

Since the Brexit vote, the prime minister has faced pressure to call for a new election and obtain a new mandate to push forward with negotiations with the EU.