Sir Keir Starmer must use his party's conference to confirm the direction he intends to take Labour in and how he will hold the party together, Norwich MP Clive Lewis has said.
Labour's annual conference - the first in person for two years - started in Brighton on Saturday in what is being seen as a make-or-break moment for its leader.
Sir Keir's recent essay The Road Ahead, for the Fabian Society, was seen by left-wingers as putting the party on the road to more centrist ground.
And Norwich South Labour MP Clive Lewis said: "I'd like to see the leader set out a clear and bold manifesto which does not go back on what he stood for when he was the unity candidate.
"It's really important that he confirms where he is heading and how is going to hold the party together."
Mr Lewis, who will take part in a discussion on the benefits of a progressive alliance on Tuesday, is also keen to get a commitment on proportional representation and clarity over a Green New Deal.
Some 139 local party groups also submitted motions pushing for Labour to support a change to a proportional representation electoral system.
That was backed by pressure group Compass in a report released ahead of the conference.
Mr Lewis said: "I'd like some clarity on the Green New Deal and a commitment to radical electoral changes, starting with proportional representation.
"We need a visionary overhaul of Westminster that transforms and democratises Britain.
"We should go further than just asking people to hand us power, by ending Westminster’s business-as-usual by giving power to them.
"That starts, but does not end, with a commitment to making every person’s vote count equally through the introduction of proportional representation."
The conference will include two motions on climate and ecological justice and Mr Lewis has urged fellow members to support them.
Sir Keir will make a speech on Wednesday, following The Road Ahead essay, where he said the party cannot "wait around for the public to decide we are right" and must instead grasp the opportunities the current political atmosphere provides.
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