Which US president refused to recognize Thanksgiving?

In Thomas Jefferson’s time, Thanksgiving as a national holiday didn’t exist at all. The formal observance of Thanksgiving Day only began in 1863, when Lincoln proclaimed the holiday in response to the horrors of the Civil War. For Jefferson, supporting Thanksgiving meant supporting state-sponsored religion, and it was his aversion to mixing church and state that earned him a reputation as America’s only anti-Thanksgiving president.

Source: History