Perhaps this is something the workforce can resolve. The issue is cost, and the off-shore competition is providing a lower cost. Rather than just letting the jobs go, the workers being terminated should fight for a chance to counter bid that offer.
The local workers do not have to beat the price, just beat the price for value. What they have to offer is knowledge specific to the company, location that allows direct interaction with the company versus phone/email or high travel costs. Add to that a decrease in their labor cost and if they are within 10 to 20 percent of the offshore competition they should be able to win the bid.
Now this means setting up their own company, probably a reduction in benefits and certainly a reduction in wages, but there is opportunity as well. As their own company, they can internally link profits to workers in a fairer approach. They can probably negotiate a cheap lease on their otherwise empty work space from the company. They are free to market their expertise to other firms as well to increase profits.
As for counting on taxes or tariffs, it is a poor approach that rarely does more than provide short term relief. This is a global economy now, and we have to play by global rules.
On the side, consider investing as a group in the stock of companies offshoring. Build a big enough voting block and throw the greedy bastards out on their rears!