Sen. Bernie Sanders announced on Tuesday that he's running for president in 2020.

At age 77, if Sanders were to win he would be the oldest president by seven years – a record that President Trump currently holds.

If former Vice President Joe Biden, decides to run, he would also be a contender for oldest president, at age 76. However, there have been rumors that he is concerned about his age affecting his decision to seek the White House.

Before Trump, the oldest elected president was Ronald Reagan, who took the oath of office at the age of 69 in 1981.

Check out where all the US presidents stand in the graphic below:

As many Democratic presidential candidates prepare for a crowded primary, age often comes up when discussing if someone is fit for the White House.

On Tuesday, Senator Bernie Sanders announced that he would run again. If he were to win, he would become the oldest president – besting President Donald Trump by seven years. At age 76, if Joe Biden decides to run, he would also be a contender for the oldest person to take the White House.

However the range of ages for 2020 candidates is vast. South Bend, Indiana Mayor Pete Buttigieg just turned 37, making him the youngest to enter the race.

Congress is seeing an increase in younger members as well. In January, 29-year-old Alexandria Ocasio-Cortez became the youngest member of congress, contributing to a 420% increase in millennial members.

Despite this younger wave of political participation, the most common ages for presidents remains in the 50s.

While Obama was the fifth youngest president at the start of his first term, President Trump was the oldest to be inugurated at age 70.

Here's a list of all of the presidents in order of youngest to oldest: