specifically Article !!, Section 4:
The President, Vice President and all civil Officers of the United States, shall be removed from Office on Impeachment for, and Conviction of, Treason, Bribery, or other high Crimes and Misdemeanors.
Members of Congress are NOT civil officers.
Article 1, Section 5 provides that:
Each House shall be the Judge of the Elections, Returns and Qualifications of its own Members, and a Majority of each shall constitute a Quorum to do Business; but a smaller Number may adjourn from day to day, and may be authorized to compel the Attendance of absent Members, in such Manner, and under such Penalties as each House may provide.
Since Article 1, Section 2 provides, in part, that:
The House of Representatives shall chuse their Speaker and other Officers; and shall have the sole Power of Impeachment.
And Article 1, Section 3 provides, in part, that:
The Senate shall have the sole Power to try all Impeachments. When sitting for that Purpose, they shall be on Oath or Affirmation. When the President of the United States is tried, the Chief Justice shall preside: And no Person shall be convicted without the Concurrence of two thirds of the Members present..
that would mean that the House could impeach a Senator without the Senate having any say whatsoever (other than to refuse to hear said impeachment and the House could not expel a member without the concurrence of the Senate.
That conflicts directly with Article 1, Section 5, which provides that each house shall determine the qualifications of their members as well as this provision, "Each House may determine the Rules of its Proceedings, punish its Members for disorderly Behaviour, and, with the Concurrence of two thirds, expel a Member".
Have you ever taken a civics class?