However, those tools of party control increasingly alienated voters in the mid‐​20th century. Many in both major parties were frustrated by the consensus politics of the post‐​World War Two era, in which the parties hewed towards the political center, pushing both the Right and the Left to the margins. Progressive Democrats liked Truman no more than conservative Republicans liked Dwight Eisenhower, who was, after all, recruited by both parties to run as their nominee. Thus, when the New Right and New Left burst through the political levees in the 1960s, there was immense pressure to reform the party system and nominate candidates that reflected the will of party members rather than the machinations of party elites.

The most significant of these reforms was the binding primary. The first primaries dated back to the nineteenth century, but they were non‐​binding, turning them into little more than “beauty contests,” as political observers called the New Hampshire primary in 1952. (Although Truman’s surprise defeat in that “beauty contest” may have convinced him not to run for re‐​election.) That changed as a result of the 1968 election. President Lyndon Johnson, despite being mired in the unpopular Vietnam War, was considering running for reelection. But the rising anti‐​war faction of the Democratic Party preferred Eugene McCarthy, a Senator from Minnesota who had taken a strong stance against the war. McCarthy’s campaign shocked the party establishment after he came uncomfortably close to beating Johnson in the New Hampshire primary, in large part because of energetic support from his young, college‐​age volunteers who reporters gave the derisive nickname of the “childrens’ crusade.” (Half a century later another politically radical senator with a large contingent of enthusiastic, young supporters would outperform expectations in New England.)

His uncomfortably narrow win in New Hampshire convinced Johnson not to run for re‐​election. That led to a particularly chaotic primary field, especially after the assassination of presumptive frontrunner Robert Kennedy. McCarthy went on to win a majority of primary votes, leaving Johnson’s final heir apparent, Vice President Hubert Humphrey, to limp into the 1968 Democratic National Convention in Chicago. Despite the lack of party enthusiasm for Humphrey, party leadership calculated that McCarthy’s strident anti‐​war position would hurt their chances in the general election. So the usual wheels began turning, the gears of party control started grinding, and the convention nominated Humphrey. That led to an eruption of protests outside the convention hall in an embarassing, nationally‐​televised spectacle that likely contributed to Humphrey’s loss in the general election to Richard Nixon. (It also led to the nomination of what was arguably the finest Presidential candidate to ever grace the political stage: Pigasus, the 145 lb pig nominated by Yippie protestors before being eaten by the Chicago Police Department.)

Democratic Party leadership realized that in order to keep the next generation of party members from leaving for more radical alternatives, they needed to reform the nomination process. The resultant McGovern‐​Fraser Commission proposed changes before the 1972 election, the most sweeping of which was to make primaries binding on most of each state’s delegates. It was the end of an era in which candidates could win the primary process but lose at the convention. And, in so doing, it took away one of the key tools of control over the nomination process. Party leadership would have a much harder time defying the will of rank‐​and‐​file membership in order to select more moderate candidates.

However, these reforms, although calming the turmoil within the Democratic Party, also led to a series of nominees that struggled to compete on the national stage because of their progressive policies. What played well with the further Left‐​leaning contingents of the Democratic base in the primaries did not play as well with the electorate in the general election. That list of ideologically‐​consistent but doomed nominees included the titular head of the McGovern‐​Fraser Commission, George McGovern, a progressive senator from South Dakota who lost badly in the general election to Richard Nixon in 1972.

Eventually, the Democratic Party recalibrated its nomination process to give back some control to party elites, creating the “superdelegate” system in 1982 that reserved a substantial minority of unbound delegate positions filled by the party leadership. The Republican Party never adopted the more top‐​down, nationalized delegate system of the Democrats, preferring to leave primary design decisions to its state parties, but, even though implemented on a state‐​by‐​state basis, binding primaries became the norm for Republicans as well by the 1980s. Voters on both sides of the aisle demanded a more democratic process.

At first blush, it might seem like the rise of the binding primary should have fatally undermined the Van Buren‐​esque modern party system. After all, party leaders could no longer use the nominating convention to control the nomination process. However, by the 1970s, both parties had other tools at hand that could replace the disciplinary function of the nominating convention.

The first tool was the debate stage. While there were sporadic primary debates between candidates on radio and television in the 1940s and 1950s, the practice did not become commonplace until 1968, on the cusp of the McGovern‐​Fraser reforms. Televised debates became vitally important in the new era of binding primaries given that candidates now had to fight for rank‐​and‐​file votes rather than just appealing to party elites. But the party leadership controlled access to the primary debate stage and could use the debate qualification rules to push out candidates who they perceived to be too marginal or radical. They could also limit the number of debates or push them to poor time slots in order to protect an incumbent or other favored candidate from scrutiny.

The second tool was the donor list. Donations are the lifeblood of political campaigns, but, in the pre‐​digital era, the easiest path to political contributions ran through party‐​controlled donor lists. Both Republicans and Democrats not only kept track of high dollar donors but also cultivated relationships with them. Those relationships made it possible for party leaders to lean on donors to give or not give to particular candidates. Besides, wealthy donors preferred general election winners–and the possible rent‐​seeking benefits of political patronage that would follow–so their interests aligned with party leadership more often than not when it came to selecting centrist candidates with the best shot at victory.

So just as they lost one major tool of control over the nomination process, the parties found two sufficiently powerful substitutes. Marginal or radical candidates would now find it hard to make it onto the primary debate stage. If they cleared that hurdle and perhaps even went on to win a few delegates in the early primaries, that was fine. But if, at some point in the primary contest, the party leadership decided it was time to unify behind a single, generally‐​palatable candidate, they could then turn off the donor tap. It might not look exactly like the modern party system that Martin Van Buren conjured, but it functioned quite similarly.

However, by the end of the twentieth century, these two vital tools of party control were themselves under threat from new technologies, in particular the rise of conservative mass media and online crowdfunded political campaign. The writing was on the wall for the modern party system, but nobody knew how to read the signs until it was much too late.

Part Two of this series coming soon. Trump is a symptom, not a cause.