The Tories dropped by 10 points in the polls in the first week of the campaign. That could grow as the public gets to know Theresa May

May wants to fight on Brexit and leadership: the voters want a wider debate. Even prime ministers with overwhelming press support cannot dictate the agenda

Labour have narrowed their polling gap slightly with the Tories over the past week (BBC/PA Wire)

Could Theresa May regret subjecting herself and the country to the one of the longest election campaigns in living memory?

If I were her I'd be a little concerned. The polls are moving against her, and relatively small movements in support for the parties get amplified in the statistics about the "lead". That prompts unhelpful headlines and nerves. It was inevitable though.

First, even applying a sensible discount, she underestimated Jeremy Corbyn, and Tim Farron for that matter. Unlike her, they visibly enjoy campaigning, meeting voters, tussling with hecklers and wisecracking (as in the still unexplained Farronism "smell my spaniel"). May palpably finds the whole business, even in genteel Maidenhead, irksome. Cutting herself off from ordinary folk, refusing TV debates and ignoring the reporters is doing her no good.

Her rivals are also picking up momentum because of this – and in campaigns that matters. Corbyn, such has been the media vilification of him, only has to be able to string a sentence together and walk and talk at the same time to exceed expectations. Digging up old stuff about what he did in the 1980s about Palestine or something doesn't matter much to the voters of 2017. They already know he's an old leftie. All it does is show he sticks to his guns and, in the case of talking to the IRA, he got there a decade before John Major and the Conservatives did. Man of Principle and all that. As for Boris Johnson and "mugwump", well it just reminds the public how muddle-headed Bozza can be too. It just makes Labour supporters more determined to get out and vote out of resentment, as personal abuse always does. Can the Tories keep the Foreign Secretary locked away till June? They ought to.

Perversely, then, the more exposure Corbyn and Farron have on TV, the more the voters will see that they are not the idiots the press tells them they are. In an ultra-long campaign, about twice as long as normal, the Opposition leaders will correspondingly increase the leverage the Representation of the People Act gives them. May did not factor that in.

More importantly, the Labour vote may well be more resilient in the North and London than May and her advisers thought. London is firmly pro-EU and vast swaths of the North are still not convinced the Conservatives are for them. Across the country, poorer pensioners – still certain to vote – will not like what the Tories are telling them, or hinting, about the triple lock on the state pension. They're not stupid and they can see what's coming; clearly Theresa May doesn't appreciate their ability to see through a pledge such as the one made on Marr that the pension will rise every year. They want to know by how much and they want what they have now. They need a responsive NHS too. Underestimate them at your peril. Cameron and Osborne did not – and that's how they won before.

May's robotic lines about strong and stable leadership are also attracting derision. What we've had since last June has been fairly unstable and chaotic, for a start, but the PM is becoming a figure of fun as she tries to keep the election on her territory, armed only with a pretty silly soundbite. The stuff about needing a strong mandate for Brexit has been exploded, and people see it for the expedient U-turn it really is. Frankly she's had an unstable and weak start to her bid for a vote of confidence.

Events, arguments and gaffes soon push the election into places you do not wish to go. May wants to fight on Brexit and leadership: the voters want a wider debate. Even PMs with overwhelming press support cannot dictate the agenda. So it is proving.

Then there is tactical voting. The longer the election goes on the more chance there is of the voters waking up to this. There are small signs of it now, especially among EU Remainers, and in the Green Party which is even standing down in some areas for Lib Dems or Labour. Ukippers are doing the same for the Tories, though some of their protest vote may just stay home next time. The net effect of all this is highly unpredictable, but tactical voting by Labour and Lib Dem supporters was one of things that punished the Tories so badly in 1997. That obviously won't happen again to the same degree, and there is a Tory-Ukip cross current, but under first past the post it could leave the Conservatives at a net disadvantage. It will see Sir Vince Cable back in the Commons at any rate, and push the Tories' hoped-for landslide back.

The country doesn't want one-party rule that doesn't reflect or heal its divisions. May's rhetoric goes against that grain and is alienating potential support. She isn't Thatcher and should quit trying to emulate her. It'll start to look very daft indeed.

Thus far, then, the Tories are fighting quite a retro campaign, like it is 1983 all over again. Corbyn as the pacifist romantic socialist Foot, a divided Opposition; May as Thatcher, a strong woman leading a United Tory party in government; the Conservatives enjoying propaganda-like coverage in the newspapers – the parallels are certainly there. Yet the simplistic messages do not match the greater sophistication of the voters and the new media landscape. May and her shadowy PR advisers are just not as good at politics or as modern as Thatcher and Saatchi were back then. Maggie ran a Blitzkrieg campaign, her fast-moving tactics and policy arguments leaving her underprepared enemies foundering: Theresa is trying to do the same through an interminably dull trench war of attrition, lobbing the same old slogans across no mans land into the electoral mud, missing targets and doing little damage after the first bombardment. Her enemies have been given all the time they need to match her organisation and regroup, and they enjoy life in the political trenches. I don't know about lions, but the Tories' generals are tactical donkeys.