Noah Millman wonders why the Republican “bench” of plausible presidential candidates is perceived to be so much stronger than the other party’s:

Presidential candidates tend to emerge from other high political office – the Vice Presidency, governors’ mansions, the Senate – or, much more occasionally, from other exalted perches of our national life. The GOP currently controls significantly more governorships than the Democrats do, so that immediately gives them a larger bench. But apart from that, I’m hard-pressed to identify what makes the GOP bench stronger.

I have sometimes wondered the same thing. My conclusions remain more or less the same. Clinton’s candidacy is, of course, a major factor in making the Democratic “bench” seem much weaker than it is, but it is not the only reason why it appears this way. Any party that has controlled the presidency for eight years has already used up many of its once-promising rising stars as administration appointees, and because partisans support the president of their party there are strong incentives against speculating about a future presidential run. Speculating about the succession is often viewed as a criticism of the incumbent, and unless a president is remarkably unpopular in his own party this is discouraged. That inevitably makes the “bench” of the incumbent party seem weaker, because so few partisans want to be seen as openly promoting a new leader when the current one still has years left in office. Meanwhile the out-party can indulge its fantasies about every possible candidate that it can find. Obama’s presidency has also been bad for Democratic candidates in Congress and in the states. Many potential future candidates have lost their most recent elections and won’t be seeking higher office, so the pool of politicians from which to draw potential candidates has definitely been reduced. That accounts for a part of the difference, but it doesn’t fully explain the difference in the way the two parties’ potential candidates are perceived.

The GOP differs from the other party in that it has a supporting conservative movement that is filled with activists and pundits that are constantly looking for the Next Conservative Hope. That means that conservative activists and pundits typically spend an inordinate amount of time identifying prospective candidates many years before the next presidential election, and they then go out of their way to promote and exaggerate their virtues. Walker’s presidential boomlet may appear to have just started in the last two weeks, but he has been promoted as a possible presidential or vice-presidential candidate for years. Conservative Republican would-be candidates usually don’t have to convince activists that they’re qualified to be president, since many of the activists decided long ago that they are. As I said back in 2013:

No matter how lacking in qualified presidential candidates the Republicans may be, movement conservatives usually deem their “bench” to be overflowing with available talent.

This also means that there is a receptive audience when any Congressman, senator, or governor wants to raise his profile by hinting at a presidential run, and activists also welcome and even encourage long-shot campaigns by non-politicians and movement favorites (see Carson, Ben). With the rise of so many conservative media outlets in the last twenty years, there are additional incentives for people in the party to gain a following by launching a quixotic presidential campaign. There is simply nothing comparable to this on the other side. Democrats may occasionally have protest and single-issue candidates in their presidential fields, but on the whole they aren’t taken at all seriously. There may be a Draft Warren effort, but that is an effort to try to get at least one high-profile challenger to run against the prohibitive favorite. It seems that a lot of Democrats look at their top politicians and struggle to see them as potential presidents, while many Republicans see potential presidents everywhere they look and make a point of boasting about it.