As a matter of fact, this occurred in 1920. Eugene V. Debs ran for President and received 3.4 percent of the popular vote while in prison! That was a lot in 1920 for a Socialist.

According to Article II, Section 1, Clause 5 of the Constitution, a person must meet the following criteria to be eligible to run for President:

1. Be a natural-born citizen of the United States.
2. Be at least 35 years old.
3. Have been a resident of the United States for at least 14 years.

The Constitution does not mention felony convictions as a disqualification for running for President. Therefore, a felon can run for President as long as they meet the other eligibility criteria.

The one area that might cause problems is at the state level. Various states have restrictions for felons running for office. I’m sure there will be legal rangling but there is no Federal restriction. Some states may try to keep Trump off the ballot but there is always write-in. If anyone can pull it off Trump can.