Democrats are hoping to make big gains in this year’s midterm elections by building on the momentum gathered last November as they seek control of Congress. But before Democrats can wipe away Republican congressional majorities and deal a blow to what remains of President Donald Trump’s legislative majority, they need to resolve a series of contentious primaries pitting progressive challengers against the Democratic Party establishment. Sen. Bernie Sanders (I-VT), who unsuccessfully sought the Democratic presidential nomination in both 2016 and 2020, is spearheading many of these progressive insurgencies. Rep. Alexandria Ocasio-Cortez (D-NY), who may be the top progressive candidate for the 2028 Democratic presidential nomination, has also been actively involved. The pair of democratic socialists have embarked on a “Fighting Oligarchy” tour, holding rallies together across the country to build their movement and to channel progressive anger at President Donald Trump’s second nonconsecutive term in the White House. Rep. Alexandria Ocasio-Cortez (D-NY) and Sen. Bernie Sanders (I-VT) helped a fellow socialist, New York City Mayor Zohran Mamdani, win both the Democratic primary and the general election. (Heather Khalifa/AP) Left-wingers in blue cities also protested Trump’s deportation agenda after two American citizens were killed in Minneapolis shootings involving federal immigration authorities. While these demonstrations are gaining traction among mainstream Democrats, progressive activists have led the charge. As soon as March, progressives are going to begin to test centrists and liberals aligned with the party’s governing class. Sen. Dick...