The basic dynamic here should be familiar. When Democrats decided about ten years ago to stop pushing for gun control legislation, that didn’t take the issue off the table it led to a wave of envelop-pushing pro-gun bills. When the GOP temporarily stopped opposing Social Security in the wake of World War II, it led to 30 years of steady increases in Social Security benefits and eligibility. Every conservative retreat from anti-gay bigotry inspires people to push deeper for equality. As long as a large minority of the public thinks people should be thrown in jail for having an abortion, we’ll either see continual fighting on this point or else continued slippage as the debate loses an anchor on the pro-choice side.
You can only win politicial fights by, erm, actually fighting rather than pre-emptively capitulating. It’s a lesson many liberal and soft left parties find hard to learn. In some cases, as with e.g. the way in which the Liberal Democrats surrendered so many of their own policies in order to form a coalition with the Tories, this is caused by a disconnect between electorial rhetoric and the party leadership’s true values. In other, as with the trouble the Dutch green party GroenLinks found itself in regarding a new Dutch mission in Afghanistan, it stems from being too eager to be seen as a serious party in a media climate more hostile towards leftwing than rightwing values.