(Reuters) - The U.S. Senate’s intelligence committee is seeking documents from Donald Trump Jr. and intends to call on him to testify before lawmakers, a Senate source told Reuters on Tuesday after Trump Jr. released an email chain citing Russian support for his father before last year’s U.S. election. The source said there is no date set yet to hear testimony from U.S. President Donald Trump’s eldest son, and that the committee is in the process of sending Trump Jr. its request for information.  