Not a specialty of mine, but it depends a bit on what you mean. Franklin Roosevelt, aside from the background of his class, ended up with an accent with many stereotypically "British" features as a result of his education at Groton.

While JFK for many Americans had a stereotypically "Boston" accent the entire Kennedy family is supposed to have returned from their father's time as ambassador in London with inflections of a British accent, producing a hybrid "Kennedy accent." This too is hard to judge, however, given the Kennedys' class background.

If you mean in the earlier period after independence, this has been discussed extensively on the sub before: https://www.reddit.com/r/AskHistorians/comments/27pea7/when_did_the_american_accent_first_become/

and it effectively has its own section in the FAQ: https://www.reddit.com/r/AskHistorians/wiki/language