Labour divisions will be on show again today as MPs take up three contrasting positions on a Commons vote to renew the Trident system.

Jeremy Corbyn will be voting against renewal, Shadow Foreign Secretary Emily Thornberry and Shadow Defence Secretary Clive Lewis will be abstaining, and deputy leader Tom Watson plans to vote in support of renewal. Over 100 Labour MPs are expected to back renewal.

Watson has argued that official Labour Party policy remains to support renewal of Trident, but sources close to Corbyn have said simply that it is a policy “under review” since the review into the party’s defence policy began in January.

Emily Thornberry, who was put in charge of the review after being made Shadow Defence Secretary in the new year reshuffle, said that she was due to report back in the week following the EU referendum, but that the Leave vote had put things on hold.

Thorbnerry, now Shadow Foreign Secretary, told the Today programme: “We were going to deliver the week after Brexit, but Brexit happened and that has an effect on all of the factors.” She added that “the Labour party has to come to a collective decision by collecting evidence in a proper way.”

“Money is important, particularly at a time of financial stress,” said Thornberry, who is in favour of unilateral disarmament. “I think it is reckless for us to plough on ahead with the most expensive of all the various options and there are step-downs we can take.”

She confirmed that she would be abstaining on the vote along with Shadow Defence Secretary Clive Lewis in an article for The Observer yesterday. They accused the Conservatives of “playing games with the Labour Party and trying to embarrass us” rather than taking a reasoned approach to the defence system.

John Woodcock, who writes for LabourList on the topic this morning, had looked into using his right as chairs of the Parliamentary Labour Party (PLP) defence committee to set out Labour’s pro-Trident policy from the despatch box today, in what would have been an unusual move. However, it appears that he will be unable to do so as Corbyn will address the House from the frontbench – and the party seeks to avoid a replay of the crucial Syria vote last year, where different positions were set out from the Labour side of the despatch box. There is some speculation among MPs that Corbyn may have to set out Labour’s policy before arguing against renewal.

Writing in The Guardian, Tom Watson said that abstaining on the vote would be “an abdication of responsibility”, and criticised leaders of trade unions who were continuing to back unilateralist Corbyn despite their members’ jobs relying on the Trident system.

“Labour’s policy on Trident is clear,” Watson wrote. “But our MPs have been offered a free vote because there is a difference of opinion in the Shadow Cabinet. I support that. But those MPs who vote against Trident should be in no doubt that they are voting to put tens of thousands of defence engineers out of work, many of them members of Unite and the GMB. If you are a union general secretary supporting a unilateralist politician, you do so in the knowledge that thousands of your members may lose their jobs.

“Some argue that Labour should abstain tomorrow, citing the current Labour defence review as justification. Yet to do so is an abdication of responsibility. No matter what low cunning has engineered this vote, MPs have a duty to take a position. We cannot say to the country that we haven’t made up our minds on strategic defence.”

Owen Smith and Angela Eagle, the two challengers to Corbyn in the leadership race, are both expected to vote in favour of renewal.