A group of political scientists and law professors have recently released a report on how to improve the presidential nominations process for major parties. See it here. It explains the history that between the 1830’s and 1968, major party presidential nominees were determined mostly by political party insiders, especially Governors, members of Congress, and state party chairs. Starting in 1912, a minimum of states used presidential primaries, but the nomination remained in the hands of party leaders, especially in years in which the party did not have an incumbent president running for re-election.
The report strongly implies that the old system worked better, but the authors don’t see a path to returning to the old system. But the authors do recommend stronger party control over the process. They recommend that presidential primary candidates must first undergo a vetting process, in which national parties set up panels to decide whether to recommend candidates or not. The authors approve of the Massachusetts system in which candidates can’t get on a primary ballot without 15% delegate support at a pre-primary party meeting. They also approve of the behavior of the California Democratic and Republican Parties, who regularly hold endorsement meetings before the primary. However, they recognize that it would be very difficult to set up national endorsement meetings.
The authors also recommend a shorter presidential primary calendar, but various experts have been recommending that idea for decades. Only a federal law controlling the primary calendar could make that idea happen.
The authors recommend that presidential primaries select delegates proportionately on a statewide basis, and they criticize the process in some states in which each U.S. House district elects its own delegates. They favor superdelegates. They suggest that parties should choose delegates who are skilled in negotiating ability, in case the presidential decision is made by a brokered convention.
Nothing is said in the report about which voters should be eligible to participate in presidential primaries. But since the authors want stronger party control, the implication of the report is that closed primaries are superior to primaries in which non-members of the party participate.