> No, it hasn't
This was a 2 minute search of Google Scholar:
^1 "...the mainstream press in America operate within a narrow range of liberal beliefs... only a narrow band of liberal thought is supported by the press"
^2 "Our results show a strong liberal bias"
[1] https://www.researchgate.net/profile/Jim_Kuypers/publication...
[2] https://academic.oup.com/qje/article-abstract/120/4/1191/192...