Dave Karpf has a great piece entitled, “Cyclical patterns in activist politics: what do we know about the politics of opposition”? Karpf argues that opposing a government looks very different from the “politics of articulation” (trying to develop and promote an agenda). These are some key differences:

1. Opposition unites. As Karpf notes, the Tea Party formed to oppose Obama before he had made any policy decisions. Its original rhetoric–and its very name–implied opposition to tax increases. But Obama mainly cut taxes. That was no problem for the Tea Party, which shifted to opposing the Affordable Care Act. It was nimble about policies because its raison d’etre was opposition to a person, his core values, and the institution he controlled.
2. Rapid response becomes more valuable. Especially in the age of social media, activist networks are good at getting people out quickly. They are much worse at sustaining pressure, negotiating, and achieving new policies. When your side shares formal power, rapid response is relatively unimportant. But when the main goal is to block policies coming from the other side, rapid response pays.
3. By the same token, it becomes harder to advance a positive agenda when a movement must spend all its time blocking new initiatives from the government.

I would add two hypotheses:

4. I think activists on the left will shift from soft, proximate targets to confront their main ideological opponents. The global justice movement of the Clinton era criticized transnational corporations and the governments that supported them, yet it gained attention for protests outside the World Bank, which funds development projects. Occupy Wall Street claimed to target Wall Street, yet it got the most traction in conflicts with Democratic big city mayors and state universities that were simultaneously facing budget cuts from conservative legislatures. The environmental movement focuses on massive destruction caused by fossil fuels but achieved a notable victory by pressuring a Democratic president to block a specific pipeline that could be easily bypassed. The left tends to confront near-allies for showing hypocrisy or weakness, but that impulse fades when explicit opponents take control. (See Bayard Rustin’s absolutely indispensable and totally timely 1965 article “From Protest to Politics” for a similar point.)
5. Maintaining political discipline will be an enormous challenge. As Rustin reminded his fellow Civil Rights leaders in 1965, the point is to win. That requires mobilizing and inspiring a majority of Americans, not just fellow travelers. National Review’s Jim Geraghty tweeted earlier today, “Anti-Trump protesters are gonna take the bait, aren’t they? They’re gonna burn flags, thinking they’re irking him, but alienating majority.” It’s very hard for any large, loose network to remember what the majority of people value, let alone maintain message-discipline. Whether anti-Trump movements can manage that task is enormously important.

See also: we need SPUD (scale, pluralism, unity, depth); to beat Trump, invest in organizing; building grassroots power in and beyond the election; and democracy in the digital age.