The Progressive era invented primaries--originally in Wisconsin, the home of Robert LaFollette, to take party nominations away from corrupt party bosses and put them in the hands of the people. California, another progressive state, went even further, and eventually instituted open primaries, in which Democrats could if they chose vote for a Republican candidate, and vice versa. The primary also became popular in the South, where the Democrats were the only party that could win elections, and where white supremacists could legally ban black citizens from voting in party primaries--until the Supreme Court outlawed white primaries in 1944. Many Americans do not realize how common presidential primaries had become by 1932. In that year, Franklin Roosevelt and his two leading opponents, Al Smith and John Nance Garner, contested primaries in New Hampshire, North Dakota, West Virginia, Florida, California, Massachusetts, and Pennsylvania. Some states appear to have given presidential primaries up in the next 20 years, however. In 1952, the relatively young Senator Estes Kefauver of Tennessee, whose televised hearings on organized crime had made him a national figure, became the first candidate to try to win the nomination against a sitting President, Harry Truman. His primary victory in New Hampshire helped induce Truman to quit the race, but he lost the nomination to Adlai Stevenson, who had not run in any primaries, after several ballots.
John F. Kennedy succeeded where Kefauver had failed in 1960, when primary victories in New Hampshire, Wisconsin, and above all West Virginia made him the front runner and carried him to victory at the convention against Stevenson and Lyndon Johnson, who had both skipped primaries altogether. On the Republican side, another insurgent candidate, Barry Goldwater, won the nomination in 1964 largely because of his strength in state party organizations in the heartland, but his victory over Nelson Rockefeller in the California primary also played an important role. The Democratic nomination battle of 1968 was a turning point. Eugene McCarthy in New Hampshire repeated the feat of Kefauver in 1952, when he nearly beat the stand-in candidate for President Johnson and induced him to withdraw. Robert Kennedy also sought the nomination by the primary route, but he was expected to lose the nomination to Hubert Humphrey, Johnson's successor as the establishment candidate, before his death, simply because primaries still chose so few delegates--almost none in the South, or in large states like Pennsylvania, New York, and Illinois. Humphrey won the nomination handily over McCarthy, but the 1968 convention also created a convention led by Senator George McGovern to rewrite party rules to make them more Democratic. Many more states adopted primaries, and McGovern, the most left wing candidate in the race, won against Edmund Muskie and Humphrey, pushed over the top by a victory in the California primary--only to lose disastrously to Nixon in the fall.
Jimmy Carter, an outsider from Georgia, also used primaries to become the front runner over a large field of establishment Democratic candidates in 1976--while Ronald Reagan nearly took the nomination away from incumbent Gerald Ford with the help of primary victories in 1976. Reagan easily won the nomination in 1980. The Democratic Party establishment learned to live with the primary system. Establishment candidates prevailed over insurgents or relative unknowns in 1984 (Mondale over Hart), 2000 (Gore over Bradley), 2004 (Kerry over Dean), 2016 (Hillary Clinton over Sanders), and 2020 (Biden over Sanders and Warren.) Bill Clinton used primaries to win in 1992 against some weak establishment figures, and Barack Obama did the same in 2008 against the overwhelming favorite, Hillary Clinton. The Republican Party, meanwhile, nominated the party establishment's choice consistently--George H. W. Bush in 1988, Bob Dole in 1996, George W. Bush in 2000, John McCain in 2008, and Mitt Romney in 2012. Then came the catastrophe of 2016.
Primary victories by extreme Republicans in Senate and House elections foreshadowed Trump's win. The rise of the Tea Party spawned a number of successful Republican primary challenges in the House, culminating in 2014 in the defeat of Eric Cantor, the House Republican whip. In Tea Party year of 2010, extreme Republican candidates won Senatorial primaries in Nevada and Delaware, only to lose the general election. Something similar happened in Alabama in 2019, when Roy Moore won the Republican nomination to replace Jeff Sessions, only to lose to Democrat Doug Jones--who in turn lost badly to a more acceptable Republican last year. In 2012, Richaard Mourdock defeated long-time centrist Republican Senator Richard Lugar in an Indiana primary, only to lose the general election. The same year however witnessed the victory of the equally conservative Jodi Ernst in purple Iowa, and she won re-election lats year. Something similar struck the Democratic Party in urban areas in 2018, when Ayanna Pressley in Massachusetts and Alexandra Ocasio-Cortez in New York defeated long-time Democratic incumbents in primaries. No comparable Democrat, however, has yet won nomination and election to the Senate.
The rise of anti-establishment candidates in both parties--but especially among Republicans--sowed that party establishments had lost the support of substantial segments of the electorate, and Pressley's and Ocasio-Cortez's wins sent the same message. Joe Biden's nomination and comfortable election showed that the Democratic establishment remains in charge at the national level, and gave that establishment another chance to reconnect with a broad mass of voters. In Virginia, Republican politicians--who in so many states have been using various strategies to reduce the influence of Democratic voters--are now trying to reduce the influence of their own. Given Donald Trump's continuing popularity among Republican voters--which inhibited Republican Senators from convicting him and disqualifying him from a future run--that tactic is likely to backfire. It's up to the Democratic Party to show that rational, effective political leadership in a moment of crisis is still possible.