US Vice President Mike Pence says there is "no comparison whatsoever" between his use of a private email account for state business while he was governor of Indiana, and the email woes of former Secretary of State Hillary Clinton.
"There's no comparison whatsoever between Hillary Clinton's practice, having a private server that was handling classified information, destroying emails that were requested by the Congress and by officials," Mr Pence told reporters on the sidelines of an event in Wisconsin.
Mr Pence's use of an AOL email account was first reported by the Indianapolis Star on Thursday.
The newspaper said Mr Pence used the account at times to discuss sensitive matters and homeland security issues.
The account was hacked last summer, the newspaper reported.
Ms Clinton was seen on Friday looking at the front page of USA Today, which ran the headline: "Pence used personal email in office."
The image has been shared widely on social media, with many comments as to the irony of the scene.
Mr Pence said he complied with Indiana laws in his use of the email account, and had an outside attorney review his private email records and archive those related to state business.
During the campaign, Trump and Mr Pence said Ms Clinton's use of a private server broke the law and endangered national security - complaints that led their supporters to chant "Lock her up!" at rallies.
The State Department's internal watchdog said Ms Clinton's use of a private server broke department rules.
The FBI reviewed her emails for classified material, but it found that no criminal charges were warranted.
FBI Director James Comey, however, said Ms Clinton and her colleagues were "careless" with classified information.
Ms Clinton's staff turned over thousands of emails to the State Department in late 2014.
Her team said emails that were not related to government work were deleted, although they said that direction was given before lawmakers issued a subpoena for them.
A White House spokeswoman said Mr Pence was not subject to federal laws as governor, unlike Ms Clinton, and did not handle classified information.
There was "light years of difference" between the use of private email by Mr Pence and Ms Clinton, White House spokeswoman Sarah Sanders told reporters.