Boris Johnson and Jeremy Corbyn head to ITV’s studio in Salford on Tuesday evening locked into an unlikely unpopularity contest. Johnson is one of the most unpopular new prime ministers, going up against one of the most unpopular leaders of the opposition.

Deltapoll, a polling firm that has asked the same question at the tail end of the last couple of weeks, records Johnson bobbing up from a -5 rating to 4. But Corbyn sits at a dismal -43, although he has gained five points in a week.

The figures are generated by asking people if either leader is doing their job well or badly and subtracting the latter from the former. Similar trends are seen across other pollsters: Johnson hovering around zero and Corbyn somewhat lower.

But what is helping Johnson, for now, is that the prime minister remains popular with his own base – leave voters – while the Labour leader simply cannot rally remain voters in the same proportion.

Deborah Mattinson, who runs Britain Thinks, said that when asked to describe Johnson as a fictional character in focus groups “leave voters say something like James Bond, a figure who is a bit glamorous and gets things done, while remainers prefer Homer Simpson, unable to select which button to push”.

The absent Jo Swinson is not much helped either. Johnson and Corbyn are relatively well known to the British public and their ratings arguably more set, but Swinson appears to be suffering as the British public take a first proper look at her.

The Lib Dem leader’s ratings plunged from -9 to -23 in a week, according to Deltapoll. Billing herself as a future prime minister appears to have been an overreach.

Surveys and focus groups say judgments about party leaders loom in voters’ minds, despite the fact that two years of intense argument about Brexit appear to have soured perceptions about Britain’s political class.

When people were asked in September who was more effective, one pollster, Britain Thinks, found that Winston Churchill, Nelson Mandela, Gareth Southgate and even Vladimir Putin rated more highly than the current crop of party leaders.

The Conservative campaign is revolving heavily around Johnson, to the point where it is not obvious if there is a plan B if he says something flippant on television. Labour has deployed more frontbench figures, notably John McDonnell, but Corbyn has been leading event after event.

After two weeks of campaigning there has been relatively little movement in the polls, with some of Labour’s improvement accounted for by pollsters such as ICM returning to the market, whose figures show a smaller gap than those of YouGov.

But with up to 3 million viewers expected to tune in and a head-to-head format that allows Johnson and Corbyn many opportunities to challenge each other, there is a real chance of a dramatic moment or two cutting through, to be recycled endlessly online. As Prince Andrew can testify, one primetime television appearance can change everything.