Finance Minister Heng Swee Keat will deliver the keynote address at this year's May Day Rally, on his first day as Deputy Prime Minister.
He said in a speech last night that he will be speaking on how the Government will continue to support the unions to develop an adaptable and future-ready workforce.
Prime Minister Lee Hsien Loong typically makes the keynote speech at the annual May Day Rally, which is attended by some 1,600 unionists, workers, employers and Cabinet ministers.
A National Trades Union Congress (NTUC) spokesman confirmed yesterday that Mr Heng will do so instead on Wednesday.
Political observer Zulkifli Baharudin said the move, coming on the back of the announcement of Mr Heng's promotion to DPM, is "orchestrated to have a certain desired effect".
The former Nominated MP noted that Mr Heng's promotion to DPM "makes it very clear" he will succeed PM Lee as Singapore's next leader.
"For (Mr Heng) to speak at the May Day Rally is symbolic, it sends the signal that tripartism continues to be a very key part of the Government's strategy, even with a new leader," he said.
He added that many governments elsewhere that rose to power on the back of support from workers and the labour movement have seen support from that front loosen somewhat.
"Here, the PAP (People's Action Party) sees the labour movement as a key strategic ally still, and it looks like it wants the future leader to reinforce the importance it places on the relationship," he said.
PM Lee previously spoke at several May Day rallies when he was DPM, and has spoken at all the rallies since becoming Prime Minister in August 2004.
An NTUC central committee member, who did not want to be named, said the keynote address will be critical in helping union leaders chart their plans and actions for members.
NTUC president Mary Liew said the rally will be a good chance for Mr Heng to interact with workers and the labour movement as a whole.
"During his Budget speeches, he's very consistent all through the years in looking out for workers, and he has a tremendous heart for the workers," she said.
"We want to hear more from him, on how the tripartite partners can continue to work together to move forward and not take tripartism for granted."