Labour's lead has been pegged back to just two points in the latest Opinium/Observer poll as Ukip appears to be draining support from all of the three other main parties.

Ed Miliband's party has dropped back by two points to 34%, the level to which it fell after the March budget and its lowest score since late 2010, while the Tories have climbed two to 32%.

With the economy improving the Tories would, however, be hoping to aim for higher levels of support.

Ukip, despite a bad week of publicity over its advertising campaigns for the European election and its expenses, has remained unchanged since a fortnight ago on 18%.

The Liberal Democrats, meanwhile, are also unchanged on just 7% – an ominously low level of support for a party that now fears the loss of all its seats in the European parliament.

Ukip's resilience in the face of sustained attack suggests Nigel Farage's party has a solid level of backing that is largely impervious to negative press coverage.

Opinium has added Farage to its ratings survey for the first time and he has emerged with the best score of any of the four main party leaders, achieving a net tally of 0%.

34% approved of the Ukip leader's performance while 34% also disapproved.

David Cameron's personal rating has improved slightly from -11% to -8% while Ed Miliband's has fallen from -20% to -22%. 38% approved of Cameron's performance against 46% who disapproved, while 24% approved of Miliband's performance against 46% who disapproved.

Nick Clegg's net rating is -42%. 16% said they approved of his performance and 58% said they disapproved.

Opinium Research carried out an online survey of 1,965 GB adults aged 18+ from 22 April to 25 April. Results have been weighted to nationally representative criteria.