Ukip's "phenomenal" performance in the Clacton-on-Sea by-election shows that Nigel Farage's party can "really deliver", according to YouGov.
Joe Twynam, head of political and social research at YouGov, told IBTimes UK that he did not expect Douglas Carswell's share of the vote to increase from 53% in 2010 to 59.7% in 2014.
Carswell defected from the Conservative Party to Ukip in August and stepped down as an MP, triggering the by-election.
He was elected as Ukip's first MP with 21,113 votes – more than double the amount of votes Giles Watling, the Conservative's candidate, gained (8,709).
"It was a phenomenal performance by Ukip and it demonstrated, how in areas which are demographically suited to Ukip, they can really deliver," Twynam said.
"It's continuing what we saw at the European Union elections, where Ukip were clearly able to pick up votes from all sides among people who have been left behind.
"These are people who are distrusting, dissatisfied, disapproving – it's mopped up votes from all of them."
The by-election result also meant that the Liberal Democrats' candidate, Andrew Graham, lost his £500 deposit after only winning 483 votes.
This is the seventh time Nick Clegg's party lost its deposit since the 2010 General Election.
IBTimes UK asked Twynam if he thought the party should keep contending in by-elections before the 2015 General Election.
"The Liberal Democrats have to at least make some kind of effort," Twynam said. "They can't give up, they can't admit defeat, particularly with the election so close.
"They now have to differentiate themselves. How they do that remains to be seen."
Labour Defectors After Heywood?
Elsewhere, Labour narrowly held on to its Heywood and Middleton seat following the constituency's by-election as Ukip ate into Labour's vote share.
The election was called after incumbent MP Jim Dobbin passed away in September.
Labour's Liz McInnes won the by-election with 40.9% of the vote, but just beat Ukip's John Bickley to the line with a 617 majority.
"It's certainly the case that Ukip can run Labour a close second in Haywood and Middleton and they can win in Clacton, suggesting they are the only powerful opposition in those areas," Twynam said.
"They are the only party that can take northern cities and take suburbs in the south of England.
But Twynam warned that Ukip may "struggle" at the 2015 General Election next May.
"The first past the post system prohibits them from making a massive breakthrough, but we just don't know how it will go in May," Twynam said.
IBTimes UK asked the pollster if he thought Ukip could steal seats of Labour at the forthcoming election.
"Ukip gets most votes from the Conservatives, but it by no means get all of them from there," Twynam said.
"The Heywood and Middleton by-election shows that in Labour constituencies, these white working-class constituencies across the north of England, they are able to make inroads.
"Of course, what they could really do with is a defector from Labour just to broaden their support.
"They don't have that yet, but the Heywood and Middleton by-election shows there is the potential, so I image there will be a couple of Labour MPs wondering whether they are going to make the switch."