I would think a federal law is the best way to solve the problem while avoiding repeating the messy negotiations.
Many workers depend on their paycheck to survive day to day precisely because of the meager amount. In today's USA there is very few union who can back workers up while on a strike.
Edit: Part of what I meant by the third paragraph is that someone else will take the job at low pay if you work away. Thus the fact you are saying no individually has little effect on wages when the market (currently) is filled with job seekers. It takes a whole bunch of us saying no together to have an effect.
Setting a precedence that individuals are respected as valuable contributors to business and not simply Human Resources is the first step if you're on the business side. Doing what's best for yourself and the business, regardless of how hard you're perceived to be working is the first step on the employee side. There's no need to appeal to some imaginary benevolent authority to make the "bad people" be nicer.
See also: the Free Rider Problem[1], Prisoners' Dilemma[2]
As for organized bullying... well, surely you can see how well that argument applies in the other direction.
[1] https://en.wikipedia.org/wiki/Free_rider_problem
[2] https://en.wikipedia.org/wiki/Prisoner%27s_dilemma
[edit] fix spacing on links
2. Improve skills and network until you can do 1)
3. Don't have children until/unless you achieve 1)
Problem solved in one generation.
1. Don't be poor
2. Don't be busy
3. Be able to have a time machine to undo previous mistakes.
Problem solved with snark.
One of the main reason people have to work so many hours is the government diverts much productivity to waste. The best example is health care spending. Americans blow 25% of GDP on it. For all this spending Americans achieve a life expectancy of 78. Mexicans achieve 76 with a far lower GDP per capita of about $13,000 and spend something like 8% of GDP on health care. From this I conclude American health care spending is essentially a wasteful racket. It's not a stretch to say Americans spend one full day a week working to pay for doctors and medicines that don't really work.
Pile on other rackets such as massive overspending on defense, over-budgeted police and fire fighting forces, over-budgeted primary and secondary education, and you easily get another day or two. Americans in productive industries are spending probably near half their work week producing to pay for government connected parasitical industries.
Legislating less work time is not the primary problem. The first thing to do is address the question of Why are we as a society blowing so much money and effort on worthless crap? Cut back on the massive levels of waste and there will be more wealth with which people can choose how to spend their time, working or not.