Social influence is ubiquitous in politics and online social media. Here we explore how social signals from partisan crowds influence people's evaluations of political news. For example, are liberals easily persuaded by a liberal crowd, while resisting the influence of conservative crowds? We designed a large-scale online experiment (N=1,000) to test how politically-annotated social signals affect participants' opinions. In times rife with misinformation and polarization, our findings are optimistic: the mechanism of social influence works across political lines, that is, liberals are swayed by majority-Republican crowds and vice versa. At the same time, we replicate findings showing that people are inclined to discard news claims that are inconsistent with their political views. Considering that people have adverse reactions to politically dissonant content but not to social signals from the out-group, we point to the possibility of depolarizing social rating systems.