Beliving it is an x-risk is not fringe. It's pretty mainstream now that there is a _risk_ of an existential level event. The fringe is more like Yudkowsky or Leahy insisting that there is a near certainty of such an event if we continue down the current path.
With Hinton, Bengio, Sutskever and Hassabis and Altman all agreeing that there exists a non-trivial existential risk (even if their opinions vary with respect to the magnitude), it seems more like this represents the mainstream.
And this is all over the press and other media now, both the old and new, left leaning and right leaning. I would say it's pretty well within the Overton Window.
Politicians in the US are a bit behind. They probably just need to run the topic with some polls and voter study groups to decide what opinions are most popular with their voter bases.