Felons and the Presidency

 Samuel Strom at FindLaw:

Does a criminal indictment or conviction prevent someone from running for president?

Not necessarily. The Constitution doesn't address this issue directly. Some federal statutes (like the one that makes mishandling official records a crime) disqualify a convicted person from holding public office. Nevertheless, there is ongoing debate about whether such a punishment contravenes Article II of the Constitution.

If the Senate convicts someone in an impeachment trial, it can bar them from holding federal office. Similarly, anyone "engaged in insurrection or rebellion" against the United States cannot hold public office under the Fourteenth Amendment's disqualification clause.
Can someone who is incarcerated be president?

An incarcerated person can run for and, in theory, become president. In practice, Congress would likely find them unfit to serve because their imprisonment would hinder their ability to perform their duties.

But there's nothing legally stopping an incarcerated person from running for president. Several other people have run for president while in prison. For example, Eugene V. Debs ran for president while incarcerated, receiving almost one million votes.

However, if someone were elected from behind bars, they would likely struggle to perform their presidential duties. In that case, they might be found unfit to serve and removed from office under the Twenty-Fifth Amendment.