Jeremy Corbyn will visit a 10th Tory-held target seat since the general election was called last Tuesday in a deliberate signal that Labour is determined to fight an attacking campaign despite the anxieties of some of its MPs.

He will give a speech about Brexit in Harlow, Essex, following visits to a string of other areas including Putney, Milton Keynes and Crawley. He will head north later in the week, when parliament has been dissolved.

Party strategists claim to have drawn up a list of almost 100 seats that could be within their sights, notwithstanding the Conservatives’ comfortable poll lead.

Since the 2017 general election, which he fought just months after seeing off a leadership challenge from Owen Smith, Corbyn’s allies have taken every key decision-making position in the Labour party. As parliament rises for the election on Tuesday, staff usually based in Corbyn’s office will finish the job of decamping to the party’s Southside HQ in Victoria.

They have been in campaign mode from the moment Corbyn announced that Labour would back a general election, and for veterans of 2017 the routine is already familiar.

Each day kicks off with an early morning conference call, chaired by the shadow chancellor, John McDonnell, and Corbyn will spend as much time as he can out on the campaign trail, meeting voters, geeing up Labour activists and generating upbeat footage for the evening news bulletins.

Andrew Murray, the chief of staff to Unite’s general secretary, Len McCluskey, has again been seconded to advise the campaign, although he is recovering from heart surgery so is not working full time. Corybn’s most senior adviser, Seumas Milne, is again overseeing communications.

Another familiar figure, Karie Murphy, is described by insiders as the most senior party official on the campaign. She was recently moved out of Corbyn’s office – partly at McDonnell’s instigation – after the botched conference coup attempt against the deputy leader, Tom Watson, but she remains influential.

Murphy fought to keep her chief of staff title and was highly visible at last week’s launch in Battersea, south London. When Corbyn gathered his shadow cabinet around him to announce on television that he was backing a general election, she squeezed into the shot as the cameras were rolling.

Despite the insistence that Labour is in attack mode, this tight-knit group has also been concerned about the threat to Labour-held seats in leave areas.

They have instituted a deliberate strategy to combat the perception that Labour’s top team is skewed toward London-based remainers. Northerners Andrew Gwynne and Ian Lavery, formally the co-chairs of the campaign, plus Angela Rayner and Rebecca Long-Bailey are expected to figure frequently in the media.

The prominence of Laura Pidcock, the party’s spokeswoman on workers’ rights, who will open Tuesday’s event in Harlow, has also been noted by colleagues,. Some MPs suggest she has been earmarked as a potential leftwing leadership contender if Labour loses the election and Corbyn steps aside.

Decisions about how to balance resources between attack and defence will be taken as the weeks go on, Labour strategists say, with the help of polling and focus groups.

They insist, however, that such methods have their limitations. One recalled a focus group in Chesterfield during the 2017 campaign which included seven former Labour voters, all of whom concluded the session saying they would not vote Labour this time. On polling night, however, Toby Perkins was returned with a healthy majority of almost 10,000, although it was slimmer than in 2015.

Jack Bond, who runs Corbyn’s social media, will be overseeing Labour’s online campaign. Instead of hiring a creative agency, as in 2017, the party is using freelancers, including videographers and photographers, to boost its capacity to produce in-house material. Labour’s upbeat campaign launch video has had 2.8m views.

The party will not finalise its general election manifesto until 16 November, when members of the shadow cabinet, trade unions and the ruling national executive committee meet to sign it off in a so-called Clause V meeting.

It then plans to produce constituency-level analysis predicting how many jobs will be safeguarded, how many workers’ wages will rise and so on as a result of Labour policies.

Some Labour MPs, however, are nervous about the risks posed by the Liberal Democrats and the Brexit party, depending on the makeup of their electorate. Many refused to vote for a general election, despite being whipped to do so, fearing their seats could be at risk or, in some cases, believing the best prospect of stopping Brexit lay in holding a referendum first.

Some insiders warn privately that the tensions between Murphy and McDonnell in recent weeks could prove a flashpoint as the campaign inches towards a climax. Asked about the pair’s respective roles, a party source said: “John is an extremely effective bureaucrat. And Karie can force through the operational things that are decided.”

One Labour MP said they feared Murphy, Milne and ultimately McCluskey, as leader of Labour’s biggest union donor, were really in control. “JohnMcDonnell thinks he’s in the driving seat, but actually he’s in a flight simulator,” he said.