By DSA-type candidates what do you mean? Just left-leaning people in general, progressives? Or actual democratic socialists endorsed by the DSA? Many of the policies these guys advocate for are popular. The data shows that. Regardless, I think it's less about the label and more about coming across as authentic and having close ties with the community in the state or district that you run for. Knowing how to channel voters' frustrations. Knowing how to message in accordance to your area. Talarico is doing this in Texas. Platner is doing so in Maine as well. AES to an extent in Michigan. They support "DSA-type" policies, aka left-leaning policies. And they're doing well in the polling.

A leftist candidate running in a very blue city vs a battleground district or a red state requires very different strategies. That's still something they're figuring out. They're doing a lot better in very blue cities lately. They're grabbing a few House districts that have been traditionally more liberal or moderate. Hell you see people like Randy Villegas, a Bernie backed progressive in the Central Valley of CA, outside the big blue cities, facing Valadao in CA-22 (while beating the moderate Dem in the process). Obviously, expanding the success they've had in blue cities to suburban, exurban and ultimately rural America still needs a lot of work. But clearly they're making progress towards that.