There are complete threads of speculations and accusations, minus the proof. If you already had the proof you wouldn't need him to release his tax returns.
This is a fishing expedition with a side of attempted amateurish manipulation ('he's guilty unless he proves otherwise by releasing his tax returns'...please.)
Liberals, who don't care about their own leaders sealing all personal records, refusing to legally comply with FOIA requests, who have been proven to have hidden subpoenaed documents and e-mails suddenly being good, responsible citizens who demand the Republican release his tax returns...it's a hypocritical joke of biblical proportions.
How about you liberals insist Obama begins obeying the law by complying with ALL FOIA requests, instead of only 30% of them....
Perhaps if Obama released all the documents he is required to BY LAW then Trump might be motivated to release documents he is NOT required to according to by law.