OTL, the Populist Party merged with the Democrats in 1896, which resulted in the Democratic Party generally becoming the left-wing party for the rest of history. Could the Populists have merged with the GOP instead? It will probably require a POD a few years back (maybe having the crash of 1893 happen under a Republican so they get desperate enough to nominate a radical), and will require getting rid of Bryan, but I think it can be done. For one thing, the western plains and rocky mountain states, the base of the Populist Party, had gone Republican in every election prior to the rise of the Populists, and the Republican ticket in 1892 was the main competition for western votes against the Populists, so clearly they had a base of support there.