Shortly after, Democrats lined up to criticize Trump Jr., who in the emails appeared to try to arrange an exchange of information with a lawyer he understood to be connected to the Russian government.
Republicans have largely stayed quiet on the latest Russia revelation involving President Donald Trump, instead focusing on postponing the August recess so they could try to pass their healthcare bill. No Republican senator has tweeted about it as of Tuesday afternoon.
Here is a roundup of Democratic senators' reactions to Trump Jr.'s emails:
As this story is still developing, we will add more reactions from lawmakers of both parties as they release statements.