As reported, Councillor Neil Poole, who represents the Ridge ward on North Lincolnshire Council, left the Lib Dems to join the Conservative group.
At a rowdy meeting of the full council, a banner reading "Judas" was unfurled from the public gallery at Pittwood House.
It came as Ridge ward resident and local Liberal Democrat chairman Richard Nixon used the public question time section of the meeting to ask council leader Mark Kirk about the morality of councillors switching sides, without letting the electorate have its say.
After the meeting, Mr Nixon said: "Neil has not only let himself down, but also let the party down and more importantly, he has let the voters of Ridge ward down.
"Councillor Poole should do the honourable thing and resign as a ward councillor and fight the seat in a by-election.
"As residents quite rightly point out, he was elected as a Liberal Democrat councillor and not as a Conservative councillor.
"Therefore, he should not be allowed to switch parties without letting the voters of Ridge ward have their say."
Councillors from the controlling Labour group also rounded on Councillor Poole at the meeting.
Councillor Len Foster said: "It is not about anything else but politics and individual survival at the ballot box next time round.
"It is a disgrace and the people of Ridge have been treated shabbily.
"Resignation should be the honourable thing to do."
Councillor Stuart Wilson said: "A lot of people voted for him as a Liberal and what have they got? A Tory."
The attack on Councillor Poole came as councillors debated a report on the political composition of the council and constitutional changes. The report also included details of Councillor John Berry, who left the Conservative group last month and now sits as an Independent member.
Mr Poole said: "The antics of the local Lib-Lab pack at the full council meeting were to be expected.
"Nationally, the Liberal Democrats are being responsible by working in a coalition Government with the Conservatives to address the national debt, which has been created by Labour's reckless spending. It is a pity the local Liberals could not follow their national colleagues' example."
And Mr Poole said the electorate would have the opportunity to have its say at next year's local elections.
He said: "There are only ten months to go before the next council elections, when all residents will have the opportunity to cast their votes.
"A by-election now would cost the local taxpayer approximately £5,000.
"In these difficult financial times, that money would be better spent in our schools and other front line services."