Vermont Sen. Bernie Sanders’ son indicated on Thursday that the senator is seriously considering running for president in 2020.

“Bernard is seriously contemplating a run in 2020 and I don’t mean a jog,” his son, Levi Sanders, said in a tweet. “I forgot to mention that he is taking his vitamins and going on long walks,” he added. (Levi has always referred to his father by his first name, he said in 2016, because his father “was a friend, not an authoritarian.”)

Bernard is seriously contemplating a run in 2020 and I don’t mean a jog. — Levi Sanders (@Celentra) January 25, 2018

I forgot to mention that he is taking his vitamins and going on long walks. — Levi Sanders (@Celentra) January 25, 2018

Levi was a senior policy strategist on his father’s 2016 presidential campaign. Sen. Sanders convened some of his top political advisers in Washington, D.C. last weekend to discuss a potential 2020 run, Politico reported on Thursday.

If elected, the 76-year-old Sanders would be the oldest elected president in history. The senator will be 79 years old by election day 2020.