Supplies – Five Forces

Can I consider labour as a supplier too in the Five Forces model? Even if they are not outsourced and they are actually our own employees?

Because I am thinking that if a large number of employees of the company are part of a labour or trade union, then the company cant exploit them much as any bad changes in the working environment will have adverse impact on the company’s operations

So in that way, bargaining power of the supplier (i.e- labour force) will be high if they are part of a trade union

So can labour be considered a supplier in the five forces model?