The Associated Press reported that Hillary Clinton had more than one device and used an iPad to send and receive emails during her time at the State Department.
Clinton has repeatedly said she opted to use a personal email account for the sake of convenience.
Now Rep. Trey Gowdy (R., S.C.), chairman of the House Select Committee on Benghazi, has requested Clinton testify to the committee in private before a public hearing. Clinton has until May 1 to testify.
"That entire argument has now crumbled at her feet," Heilemann said. " I think this is a problem that is going to continue to plague her for many, many more weeks, possibly months to come.