Complex sentence: Newspapers exacerbated those political fears into xenophobia--because varieties of radical anarchism were becoming popular as perceived solutions to poverty, and the advocates were often recent European immigrants (cf. hyphenated-Americans).
Split into simpler sentences: Newspapers exacerbated those political fears into xenophobia--because varieties of radical anarchism were perceived as answers to poverty. The advocates often were recent European immigrants (cf. hyphenated-Americans).