Jeremy Corbyn and Owen Smith will make a final push for votes against the backdrop of a crunch party meeting on who decides their shadow cabinet.
Voting in the Labour leadership contest closes at noon on Wednesday, with the two candidates seeking to make the most of the last full day of campaigning.
But distractions from the main event include a meeting of the party’s ruling body on Tuesday, with the National Executive Committee expected to decide whether to reintroduce votes for the shadow cabinet and what system to take forward – if any.
Labour deputy leader Tom Watson is understood to want full shadow cabinet elections by MPs instead of including members, an idea floated by Mr Corbyn.
It is understood Mr Watson’s proposal would also allow the leader to retain the option to sack members of the shadow cabinet.
Leadership front-runner Mr Corbyn has already said he is ready to “reach out” to Labour MPs critical of his leadership if he retains power on Saturday, when the result is announced.
But the system on how to appoint shadow cabinet members will prove key in swaying former shadow cabinet members, who resigned en masse in an attempt to undermine Mr Corbyn, to return to the frontbench.
Separately, Mr Watson has insisted anyone seeking to remove him from his elected position should “bring it on”.
He believes such a challenge would not be useful for the party following this summer’s bitter contest involving Mr Corbyn and Mr Smith.
Doubts have been cast over Mr Watson’s future after Mr Corbyn refused to deny a plot to topple him from his elected position.
Speaking to The House magazine before details of the plot emerged, Mr Watson said: “No-one exists in democratic office forever.
“If there’s a move to nominate another candidate and trigger a deputy leadership race, then let’s bring it on.
“But I’m not entirely certain it would be a useful expenditure of collective political energy, particularly after the summer we’ve had.”
Elsewhere, Mr Corbyn’s campaign team says it wants to make 10,000 phone calls to Labour members and supporters before voting closes, in what they are calling “Super Tuesday”.
And Mr Smith described his bid to become Labour leader as more important than his special adviser duties linked to the Northern Ireland peace process.
He told The Guardian: “I always thought this was the most important thing I’d ever do, having previously worked on the peace process and thought that was the most important thing I’d ever do.”
Mr Smith also voiced concerns over shadow chancellor John McDonnell, a close ally of Mr Corbyn.
The MP for Pontypridd said: “I think John is someone who is increasingly a divisive force in the Labour Party.
“I think he is a talented politician in many regards, and some of the things he’s said about the economy are right.
“But I think he thinks, unlike me, that the Labour Party is just one vehicle. And he can imagine a world in which the Labour Party falls away and something else takes its place.”
