This weekend's "No Kings" demonstrations drew an estimated crowd of millions across the US to protest President Donald Trump's policies and his willingness to push the boundaries of presidential authority.

It was a moment for likeminded Democrats, liberals and some anti-Trump Republicans to rally together at a time when the American left has little formal power in national politics.

But where do they go from here?

By most accounts, the turnout at Saturday's events - in major US cities like Chicago, New York, Washington and Los Angeles, as well as hundreds of smaller towns – was higher than expected and surpassed the first "No Kings" rally in June.

Congressional Republicans had warned that the demonstrations would be "anti-American", and some conservative governors had put their law enforcement and National Guard on alert in case of violence.