> The major networks (excluding Fox) are biased leftward because their news writers and reporters are biased leftward.

I've heard the (semi-)joke that reality has a leftward bias.

But perhaps see "The Fox News Effect: Media Bias and Voting":

> Does media bias affect voting? We address this question by looking at the entry of Fox News in cable markets and its impact on voting. Between October 1996 and November 2000, the conservative Fox News Channel was introduced in the cable programming of 20 percent of US towns. Fox News availability in 2000 appears to be largely idiosyncratic. Using a data set of voting data for 9,256 towns, we investigate if Republicans gained vote share in towns where Fox News entered the cable market by the year 2000. We find a significant effect of the introduction of Fox News on the vote share in Presidential elections between 1996 and 2000. Republicans gain 0.4 to 0.7 percentage points in the towns which broadcast Fox News. The results are robust to town-level controls, district and county fixed effects, and alternative specifications. We also find a significant effect of Fox News on Senate vote share and on voter turnout. Our estimates imply that Fox News convinced 3 to 8 percent of its viewers to vote Republican. We interpret the results in light of a simple model of voter learning about media bias and about politician quality. The Fox News effect could be a temporary learning effect for rational voters, or a permanent effect for voters subject to non-rational persuasion.

* https://www.nber.org/papers/w12169

A few years ago there was a study that showed that people who watched Fox News had less accurate views of reality than those who reported watching no news at all:

* https://portal.fdu.edu/fdupoll-archive/knowless/final.pdf

Seems to still be somewhat accurate with a more recent examination:

> Many Americans consume aligned partisan media, which scholars worry contributes to polarization. Many propose encouraging these Americans to consume cross-cutting media to moderate their attitudes. However, motivated reasoning theory posits that exposure to cross-cutting media could backfire, exacerbating polarization. Building on theories that sustained exposure to novel information can overcome motivated reasoning and that partisan sources on opposite sides cover distinct information, we argue that sustained consumption of cross-cutting media leads voters to learn uncongenial information and moderate their attitudes in covered domains. To test this argument, we used data on actual TV viewership to recruit a sample of regular Fox News viewers and incentivized a randomized treatment group to watch CNN instead for a month. Contrary to predictions from motivated reasoning, watching CNN caused substantial learning and moderated participants’ attitudes in covered domains. We close by discussing challenges partisan media may pose for democracy.

* https://www.journals.uchicago.edu/doi/10.1086/730725

* Preprint PDF: https://osf.io/preprints/osf/jrw26

> Besides, in the era of social media and podcasts, the FCC's equal time rule is antiquated.

The FCC's equal time rule does not apply to Fox News. The rule only applies to broadcasters that use public airwaves, which Fox News does not do: they are a cable-only channel.