Jeremy Corbyn will close his campaign for the Labour leadership this week at final rallies that will take the number of people he has addressed across Britain over the last three months to 50,000.

The four candidates for the leadership will make their final pitches before the close of ballots on Thursday amid rising hopes in the Yvette Cooper and Andy Burnham camps that their candidates might yet win. Cooper pointed out that by last week half of the party’s members had yet to vote.

The shadow home secretary told the Murnaghan programme on Sky News: “Half of the members and supporters have still not yet voted and I think a lot of people are considering this really carefully.”

The final week of campaigning, before the winner is declared at a special Labour leadership conference on Saturday, will be slightly curtailed as parliament returns for a two-week sitting. But the candidates will speak at final rallies across the country.

Corbyn has signed up 15,800 volunteers and seen the number of followers on his personal Twitter account grow from 32,000 to 130,000, with 105,000 on Facebook. Corbyn joked at a rally in Cambridge on Sunday night that he would never be considered a leftwinger in Germany.

Speaking to an overspill after the rally was once again packed out, Corbyn said: “If I was putting forward these ideas in Germany I’d be called depressingly moderate, depressingly old fashioned as they have a national investment bank already they invest in public services. The first thing we’ll do if we win this election is to continue to strive to democratise policymaking in the Labour party.”

Labour MPs opposed to Corbyn will seek to curb his power as leader when they call at a meeting of the parliamentary Labour party on Monday night for the restoration of elections to the shadow cabinet. The critics hope this would give Labour MPs with doubts about Corbyn the strength to challenge his authority.

Tom Watson, the frontrunner in the Labour deputy leadership contest, will say on Monday that plans by supporters of Corbyn to force every Labour MP to face a reselection battle would amount to a “charter for internecine strife”. In his final speech to Labour members before the close of ballots on Thursday, Watson will say that the mandatory reselection of MPs would lead to disunity and act as a “destructive and destabilising force”.

The intervention by Watson, a veteran of Labour’s internal battles, came after reports that Jon Lansman, a Corbyn supporter who acts as the spokesman for the Bennite Campaign for Labour Party Democracy (CLPD), is planning to table a motion at the party conference calling for the reintroduction of the system. The mandatory reselection of MPs was introduced by supporters of the late Tony Benn in the 1980s – before being abolished by Neil Kinnock – as a way of weeding out MPs opposed to the hard left.

The Corbyn campaign made clear that that it has no truck with the idea. A spokeswoman for the Corbyn campaign said: “Jeremy is all about bridge-building and he will work to unite the Labour party under his leadership so, of course, Jeremy won’t introduce mandatory reselection for sitting MPs and he has absolutely no intention of deposing sitting MPs.”

Watson, who aims to act as a unifying force if he wins the deputy leadership, does not believe that Corbyn wants to bring back the reselection mechanism, which goes further than the current “trigger-ballot system”. This means that local parties only trigger a full reselection vote if they are unhappy with their MP’s performance.

But the former minister calls on Lansman to withdraw his motion. Watson will say in his speech in Dudley: “Mandatory reselection of MPs ... is an inherently intolerant mechanism, which isn’t helpful to the process of drawing the party together. History has shown even its suggestion to be a destructive and destabilising force.

“What mandatory reselection comes down to is not rooting out the occasional bad egg, but systematically getting rid of Labour MPs some of whose views you might not share. That’s not where our energies are best spent while the Tories are waging war on disabled people and trade unionists.

“Strength in adversity comes only through unity – whereas mandatory reselection is a charter for internecine strife. We can’t afford to do that to the vulnerable people who depend on us. No leadership or deputy leadership contender supports mandatory reselection of MPs.

“So, in a spirit of comradeship and unity, I call on the CLPD to withdraw their conference motion on this. In so doing they can send a signal about the kind of party we’re going to be in the next few years. And the kind of party we’re not going to be.”

The intervention by Watson comes as the Labour MP Jonathan Reynolds, a supporter of Liz Kendall, said that Corbyn appeared set to win the leadership. Kendall faced embarrassment when Toby Perkins, her campaign manager, said that he had given his second preference vote to Andy Burnham on the grounds that he is more likely than Yvette Cooper to beat Corbyn. Perkins said he was acting in a personal capacity.