WASHINGTON — President Trump on Monday released a triumphant campaign advertisement declaring his first 100 days in office a success, and branding news media that have reported otherwise as “FAKE NEWS.”

The 30-second television advertisement and a series of more targeted versions that are to run online are the latest examples of Mr. Trump’s extraordinarily early return to politicking at a time when most presidents would be spending their time pushing through their highest legislative priorities.

It follows a frenetic week in which Mr. Trump, after having rejected the 100-day mark as an indicator of the success or failure of his presidency, sat for several interviews and dispatched his top advisers for virtually nonstop briefings. They all made the case that he had accomplished significant things since taking office, despite Mr. Trump’s lack of major legislative achievements.