The 14th Amendment to the United States Constitution, specifically Section 3, deals with issues related to treason and disqualification from public office.
Section 3 states:"No person shall be a Senator or Representative in Congress, or elector of President and Vice President, or hold any office, civil or military, under the United States, or under any State, who, having previously taken an oath, as a member of Congress, or as an officer of the United States, or as a member of any State legislature, or as an executive or judicial officer of any State, to support the Constitution of the United States, shall have engaged in insurrection or rebellion against the same, or given aid or comfort to the enemies thereof. But Congress may, by a vote of two-thirds of each House, remove such disability."
In simpler terms, this section states that individuals who have taken an oath to support the Constitution but have engaged in insurrection, rebellion, or provided assistance to enemies of the United States, are disqualified from holding public office.
This disqualification extends to being a Senator, Representative, elector of the President or Vice President, or holding any civil or military office under the U.S. or any state government.
However, Congress has the power to remove this disqualification by a two-thirds majority vote in each house, meaning that there is a pathway for individuals who have previously engaged in insurrection or rebellion to have their eligibility for public office restored.
Now it's crystal clear, isn't it?