What is the presidential line of succession? Who can step in for a president? Here's what to know.

WASHINGTON — Americans across the country have concerns about the health of their leaders, from President Joe Biden and members of his cabinet to lawmakers in Congress.

Poll after poll has shown that voters have reservations about Biden's age as he seeks another term in office. And the president's health has also been in the spotlight after a report from special counsel Robert Hur raised allegations about Biden's mental acuity.

But the president isn't the only leader whose health has recently come to the forefront. Defense Secretary Lloyd Austin was hospitalized on Sunday after developing symptoms related to a bladder issue. He was also hospitalized last month after suffering complications from surgery for prostate cancer.

That's not all. Sen. Mitch McConnell, R-Ky., appeared to freeze multiple times last year in front of reporters and his fellow lawmakers.

These leaders and other officials facing medical issues have raised questions for voters. For example, what happens if a president, or a member of his cabinet, needs to step down or cannot continue serving the American people?

That’s where the Presidential Succession Act of 1947 comes into play. It was signed by former President Harry Truman, and it outlines an order of leaders who can assume the presidency.

Here's what you need to know about the presidential line of succession.

What is the presidential line of succession?

The Presidential Succession Act states that a sitting president may be replaced if they become incapacitated, die, resign, are unable to hold office or are removed from office. The vice president can then assume the presidency.

If the vice president is also unable to serve, the next person to assume the presidency would be the speaker of the House. Then the order of succession is as follows:

• President Pro Tempore of the Senate (The vice president is also the president of the Senate, but the president pro tempore is a senator who typically presides over day-to-day business in the upper chamber)

• Secretary of State

• Secretary of the Treasury

• Secretary of Defense

• Attorney General

• Secretary of the Interior

• Secretary of Agriculture

• Secretary of Commerce

• Secretary of Labor

• Secretary of Health and Human Services

• Secretary of Housing and Urban Development

• Secretary of Transportation

• Secretary of Energy

• Secretary of Education

• Secretary of Veterans Affairs

• Secretary of Homeland Security

The line of succession wasn’t always this order. In 1792, Congress placed the Senate's president pro tempore first behind the vice president. In 1886, Congress removed both the Senate president pro tempore and speaker from the line of succession.

After former President Franklin Roosevelt died in 1945, then-Vice President Harry Truman assumed the presidency. He argued that the speaker, as the “elected representatives of the people” should be next in line after the vice president.

Truman then signed the Presidential Succession Act in 1947, placing the House speaker and the president pro tempore after the vice president.

Who follows Joe Biden in the presidential line of succession?

In order to assume the role of the presidency, an individual must be at least 35 years of age and be a natural born citizen. They also must have lived in the U.S. for 14 years.

Vice President Kamala Harris is first in line for the presidency, followed by House Speaker Mike Johnson, R-La., and Sen. Patty Murray, D-Wash.

That extends all the way to Homeland Security Secretary Alejandro Mayorkas, though he and Energy Secretary Jennifer Granholm are both naturalized citizens, making them ineligible for the presidency.

This article originally appeared on USA TODAY: Presidential line of succession list: Who can step in for Joe Biden?