Labour's triumph in the Wythenshaw and Sale East by-election was "disastrous" for the Conservatives and Liberal Democrats, and vindicates Ed Miliband's new approach, said Ivan Lewis, shadow minister for Northern Ireland.
"This was a disastrous night for the two coalition partners," Mr Lewis told ITV's Daybreak. "The big news last night was the Lib Dems losing their deposit, the Tories being shunted into third place."
"It was a vindication of Ed Miliband's focus on the cost of living crisis which is affecting the vast majority of people in this country."
But Mr Lewis conceded that the low turnout of 28 per cent was cause for concern for all parties, saying: "all of us have to face up to the fact that people do feel alienated from mainstream politicians."
Prime Minister David Cameron said that Labour's win at the Wythenshawe and East Sale by-election was not "particularly surprising", but conceded that voters were sending a signal to the Conservative party, which came third in the vote, behind UKIP.
"Obviously one would prefer to come second rather than third, but I dont think this is a particularly surprsing result in Labour holding this seat," Mr Cameron told ITV's Daybreak.
"I don't think it was the sort of break through that people were talking about," he added.
"When people know that there's a by-election, they know the government isn't going to change, but obviously messages are sent, and signals are sent and protests are made, and governments should always listen to those things and I always do."
Labour leader Ed Miliband has tweeted congratulations to Mike Kane, who won the by-election at Wythenshawe and East Sale.
Mike Kane was elected as the MP for Wythenshawe and Sale East following yesterday's by-election. He tweeted:
Ukip leader Nigel Farage has described polling second in the Wythenshawe and Sale East by-election as "massive progress".
- Mike Kane (Lab) 13,261 (55.34%, +11.21%)
- John Bickley (UKIP) 4,301 (17.95%, +14.50%)
- The Rev Daniel Critchlow (C) 3,479 (14.52%, -11.03%)
- Mary Di Mauro (LD) 1,176 (4.91%, -17.44%)
- Nigel Woodcock (Green) 748 (3.12%)
- Eddy O'Sullivan (BNP) 708 (2.95%, -0.90%)
- Captain Chaplington-Smythe (Loony) 288 (1.20%)
ITV Granada's Daniel Hewitt is at the Wythenshawe and Sale East by-election: