Something something representative democracy, where politicians have a duty to deal with the complexities, in order to actually represent the peoples interests and not just the populist ones.
Thing is, those who are against immigration are much more motivated. This is generally how politics goes, that a motivated minority can eventually get their way against a less-interested majority. As great as it is, that was largely what happened in the other direction with issues such as gay marriage.
For those who are anti-immigration this is often the only topic they care about, or they care much more about this than anything else. On the other hand, those who are pro-immigration are largely either mildly-favorable towards it or they care much more about other issues.
Personally I think that left-leaning parties in Europe basically have two options currently:
-Fight against anti-immigration stances and then lose power.
-Focus on other topics while getting tougher on immigration.
It might not be the smartest move to be anti-immigration, but unfortunately in a democracy feelings are usually more important than facts and one of the biggest issues with the left is not being able to accept that.----
Calling it an immigration debate is a symptom itself, right? We're usually not talking about people coming here to study and to work, which would be immigration. Instead the debate is about asylum for refugees, whether refugees get individual human rights or if they can be treated in bulk with imposed limits, where they can be sent and who has to deal with them, who builds walls, whether they can be drowned in the mediterranean or if it's legitimate to shoot them at the borders, whether activists who rescue them from drowning are criminals.
Stop framing it as immigration, which is a bit in each country's purview to organize or not, and can indeed be debated. Here we're talking about human rights for human beings who are in a desperate situation and deserve every help they need and if we can't grant them that then we have failed our shared values, and our economic system and our political system are apparently unsuited for humanity and should be abolished. Refugees are welcome or you are an asshole and there cannot be any discussion about this, at all, in a modern democracy with human rights.
Being anti immigration does NOT make you a nazi. It's this kind of us against them rhetoric that got us into this situation in the first place. It may make you a racist, but you can be racist and an asshole and still be a democrat and far from a nazi. The world isn't black and white, please grow up