Sinn Féin's Pearse Doherty says he fears the replacement of the wage subsidy scheme will lead to job losses.
He says he's heard from employers are being forced into decisions to "try to keep their head above water" - meaning they may have to let some employees go.
The existing scheme will be replaced from Tuesday by a new initiative which will run until the end of March 2021.
The maximum subsidy allowed will fall from €410 to €203 each week, while there will be a lower rate of just over €150 for lower paid employees.
It will apply to workers who receive weekly gross wages between €151.50 and €1,462, with no subsidy for those earning less than €151.50.
Speaking on On The Record, Deputy Doherty says the Government now needs to give more support to businesses that are struggling or not allowed to open.
He said: "There is a scheme now which goes beyond September, which is positive... and also the scheme now allows for seasonal workers to be employed.
"The problem is there are many, many negatives in terms of this scheme - and I fear it will lead to job losses.
"What we have now is a lower amount of support for businesses... there is a significant decrease for employers to continue to support their employees.
"Crucially, in terms of the lowest-paid employees, there is actually no support whatsoever for them."
Lowest paid workers
Deputy Doherty said there needs to be support for people who earn €151 or less gross per week.
He said: "When we talk about how many people are affected... there's 153,000 workers across the economy that earn below that figure."
While Deputy Doherty said it's the case that employers should pay as much of the employees' wage as they can, that's "not the reality" at the moment.
He suggested: "Their employment is supported by the State - that ends on Tuesday.
"We've heard from a large number of employers over the last number of weeks... that they're being forced into decisions to try and keep their head above water.
"The obvious choices they're making is to let the employees go that there's no support for."
He said nobody's saying resources should be used to underwrite businesses that are going to fail, and there is a need to move away from a 'blanket approach' into one offering extra supports for the worst-hit sectors.
However, he said there's a "responsibility" on the State to continue to support the likes of wet pubs and tourism businesses that remain closed.