Upton Sinclair, the famed socialist and author of The Jungle:
"The eloquent senator was explaining the system of protection; an ingenious device whereby the workingman permitted the manufacturer to charge him higher prices, in order that he might receive higher wages; thus taking his money out of his pocket with one hand, and putting a part of it back with the other. To the senator this unique arrangement had somehow become identified with the higher verities of the universe."
Of course, this was back in the days when organized labor felt secure in their capital advantage over the poor countries of the world, and supported free trade.
It is a funny quirk of contemporary America, that most of the, so called leftists in 2016 would have found themselves much more at home in McKinley's Republican party than among Bryan's Democrats back in 1896 
Not really.
Yea, that ingnores a lot of other issues at work as well. McKinely's was a party by, for and of business at a time when business wanted gold and protectionism. To that exent those issues could be sold to attract progressives and labor to win the Midwest and New York, they were as a form of wedge issues to divide working class Northerners (primarily industrial) from working class Southerners (primarily agricultural). They were hardly friends of labor or progressivism, hence the battle between TR and Mark Hanna just a decade later, and how such groups increasingly found themselves on the outside of the party looking in over the course of the early 20th century.
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