Most voters are in the center, when they pay attention; and most don’t pay attention. They aren’t interested. They just want to work and fall in love and follow sports and watch TV.
It is outrages on the right that push uninvolved voters to pay attention and become involved, that motivate them to vote, and to vote for progress. Think about Bull Conner’s thugs attacking kids with firehouses and dogs in 1963. In recent days we have the right-wing Supreme Court overturning abortion rights, or DeSantis et al banning books, etc.
The progressive left’s best strategy is to make their votes necessary for liberals to get elected and pass legislation. This is much easier in a parliamentary system (Canada, the U.K.) than in the U.S., with its two-party system so firmly entrenched. But it’s not easy anywhere.
Progress is multi-generational. One lifetime is barely the blink of an eye on history’s timeline. It is natural, from the perspective of a single lifetime, to feel enormously frustrated. And it is very difficult to take heart over incremental improvements that, with rare exceptions, began long before you were born and will not be completed until long after you die.
Start local! National politics is really, really hard to change. City councils, school boards, county commissions, and state/provincial legislatures are where progressives need to start. But this is slow, tedious work and, historically, progressives have been more inclined to street demonstrations that usually have limited (sometimes counterproductive) effects—although we tend to remember the spectacular exceptions.