A Reform surge in looming local elections could hand the Lib Dems crucial seats, according to a polling guru.
Professor John Curtice said Nigel Farage's party might not be the 'big winners' from the contests on May 1 despite high levels of support.
He cautioned that while the newcomers are taking votes away from Labour, most is still coming from the Tories - who have the 'most to lose'.
Although the battlegrounds have been narrowed by delays in some areas due to a devolution overhaul, more than 1,600 councillors are set to be chosen across 23 local authorities in the first big test since the general election.
There are also contests for six mayors, and the first by-election of the Parliament in Runcorn & Helsby following the resignation of ex-MP Mike Amesbury.
Labour's support has plunged since May, with national polls suggesting Keir Starmer's party is neck and neck with Reform and the Conservatives.
Professor John Curtice said Nigel Farage's (pictured) party might not be the 'big winners' from the contests on May 1 despite high levels of support
Sir John suggested a Reform surge in looming local elections could hand crucial seats to the Lib Dems (pictured, Ed Davey campaigning last week)
Keir Starmer is braced for difficult results in the local elections next week
Labour's support has plunged since May, with national polls suggesting the party is neck and neck with Reform and the Conservatives
Writing for the Mirror, Sir John highlighted that when the seats were last contested four years ago the Tories were 'riding high' under Boris Johnson.
'Of the 23 councils balloting next month, all but four are currently controlled by the Conservatives,' Sir John said.
'The party will be defending nearly a thousand of the 1,641 council seats at stake. Labour go into the election with fewer than 300 seats and theLiberal Democrats, with only just over 200.'
Sir John said that although one in twelve Labour voters appeared to have switched to Reform, most of Mr Farage's support still came from Mr Johnson's backers from four years ago.
He said: 'Reform UK will not necessarily end up big winners in terms of seats. In last year's general election the party won more votes than the Liberal Democrats but ended up with many fewer seats. The party's vote was spread too thinly across the country.
'In taking votes from the Conservatives, Reform could simply help the Liberal Democrats, who always do better in local elections than in the national polls, take key seats from Kemi Badenoch's party, such as in Oxfordshire.
'Despite the party's current unpopularity, even Labour might pick up some Tory seats too, with Nottinghamshire a key target.'
Sir John said Reform would be eyeing 'big gains' in Lincolnshire, regarded as the most Eurosceptic part of the country.
However, stressing the fine margins, he added that if Mr Farage's support is less 'thinly spread' it could do 'much more than that'.
The comments came after a poll suggested Reform is on course to win most Commons seats if a general election were held now.
A More in Common survey of more than 16,000 people - conducted using the so-called MRP method that maps types of voters on to individual constituencies - concluded Mr Farage's party would win 180 seats on an implied vote share of 23.7 per cent.
The Tories and Labour would be tied on 165 seats each at 24.3 per cent and 24.5 per cent respectively
Deputy Prime Minister Angela Rayner, Chancellor of the Duchy of Lancaster Pat McFadden and Energy Secretary Ed Miliband are among those who face defeat at the hands of Reform.
The model also suggests an Independent gain in Health Secretary Wes Streeting's London seat of Ilford North.
Experts stress that polls so far from a general election - not due until 2029 - should be treated with caution.
Sir John highlighted that when the seats were last contested four years ago the Tories were 'riding high' under Boris Johnson (pictured, current leader Kemi Badenoch)
A More in Common survey of more than 16,000 people - conducted using the so-called MRP method that maps types of voters on to individual constituencies - concluded Mr Farage's party would win 180 seats on an implied vote share of 23.7 per cent
But More in Common director Luke Tryl said the voter coalition behind Labour's landslide victory last summer looks to have disintegrated.
'We are a long way from a general election and trying to predict the result is a fool's errand, but what we can say for certain is that as of today British politics has fragmented to an unprecedented level,' he said.
'The coalition for change that elected Keir Starmer's Government has splintered right and left.
'Labour… having secured a historic victory now find themselves on the wrong side of a disillusioned electorate frustrated at the slow pace of change and some of the Government's early missteps.'