The republicans hold the presidency, have a majority in congress, and a majority (depending how you interpret the moderate members) of the supreme court. Even the more moderate republicans are afraid of the Trumpets so they mostly vote in-line (see for example Cassidy voting for RFK Jr).
There are some things the democrats can do but it's mostly "spanner-in-the-works" slow-downs of the process, or mid-level judges. At the same time, the democrats are in disarray with no clear leader or message.
Probably the best strategy for the democrats is to let Trump make more mistakes until even his base questions his presidency.
Democrats could do a lot with their physical bodies if they wanted to. Take a page out of classic American protest strategies: strikes, marches, sit-ins, etc.
You mean the democratic leadership, or members of the party/people-who-vote-democratic?
Protests happen in the summer mostly, and they always have a small amount of violence and property destruction (even when the protest is organized to be peaceful). Trump is just waiting around for that so he can have the military shut them down (at least, that's what he said).
Unless the protests are large enough (say, 1/4 the population of the US), and persistent, and affect business heavily. Maybe that would be enough to dispel the reality distortion/enforcement shield Trump has cast on the republicans.
People-who-vote-democratic need leaders to organize them. Their elected representatives need to be the ones heading marches and organizing rallies, not just AOC and Sanders shouldering the entire burden.
Yes, the administration will try violence, but it’s a lot harder to justify when elected officials are on the firing line.
Republicans can't vote against Trump, because the vast majority of Congressional districts are gerrymandered; this means the candidate can be easily outprimaried with just a little bit of cash. The original red map project (2010) cost about 40 million; the last map (2020) was quite a bit more expensive — perhaps 10x as much — but still quite cheap considering the benefit (functional control of the U.S. government). One of the unintended effects of the deep 2010 gerrymanders that project red map discovered was that it also distorts the Senate map (this was unknown effect, at the time). Until gerrymandering is fixed, and the legislative powers ceded to the executive are clawed back, there is no "fixing" the current situation. It was always just a waiting game for a well-heeled (for primaries) autocratically-leaning president to come along.
The Democrats can neither pass bills of impeachment (minority in the House, which introduces such bills), nor convict (a supermajority is required within the Senate, the Democrats don't even hold a majority).
Democrats can introduce bills of impeachment, but those would simply die without consideration given GOP control of the House. So far as I'm aware, none have done so since 20 Jan 2025.