About 50 protesters, many of them port workers, gave Prime Minister John Key a noisy reception when he arrived in Timaru on Friday afternoon.
Earlier in the day, workers at Prime Port Timaru had been told stevedoring is expected to finish at the port on 17 September, with the likely loss of 50 jobs.
Some of those facing redundancy greeted Mr Key outside the town's new aquatic centre with placards reading "Save Our Port" and "Please Listen".
Mr Key did not acknowledge the protesters, walking past them into the centre as soon as he arrived.
The protesters included some people opposed to partial state asset sales.
The Rail and Maritime Transport Union's organiser, John Kerr, says port management have told the workers they are trying to explore some options, but it is likely the redundancies will go ahead.
Mr Kerr says the port employs about 74 people and about 50 of them are likely to lose their jobs.
The union's general secretary, Wayne Butson, says the Government needs to have a port strategy.
"All of that investment by the region in its infrastructure now is completely valueless," he says, "and I don't think that it's right for a government to abrogate its leadership responsibilities to allow the market to determine which ports keep having ships and which ports don't."