Relatively few engineers actually want to do contract work. The day rates look high, but they have to pay self-employment taxes and health insurance, as well as charge more to cover inevitable gaps between contracts.
It seems unlikely that the existence of contract work is preventing senior engineers from joining your company. To be blunt, it’s more likely that you’re simply not paying enough to be competitive or you’re not an attractive place to work.
Without knowing more details about your specific situation, the obvious change would be to simply offer more compensation. Higher compensation can make an unattractive job more attractive.
It seems unlikely that the existence of contract work is preventing senior engineers from joining your company. To be blunt, it’s more likely that you’re simply not paying enough to be competitive or you’re not an attractive place to work.
Without knowing more details about your specific situation, the obvious change would be to simply offer more compensation. Higher compensation can make an unattractive job more attractive.