  Increased sharing of untrustworthy information on social media platforms is
one of the main challenges of our modern information society. Because
information disseminated by political elites is known to shape citizen and
media discourse, it is particularly important to examine the quality of
information shared by politicians. Here we show that from 2016 onward, members
of the Republican party in the U.S. Congress have been increasingly sharing
links to untrustworthy sources. The proportion of untrustworthy information
posted by Republicans versus Democrats is diverging at an accelerating rate,
and this divergence has worsened since president Biden was elected. This
divergence between parties seems to be unique to the U.S. as it cannot be
observed in other western democracies such as Germany and the United Kingdom,
where left-right disparities are smaller and have remained largely constant.
