................
The Constitutions structure and historical practice also indicate that impeachment likely does not apply to Members of Congress.17 First, Article II, Section 3 provides that officers of the United States are commissioned by the President;18 Members of Congress receive no such commission. Second, Members may be removed from office by other means explicitly provided in the Constitution.19 Third, the Ineligibility Clause bars any person holding any office under the United States from serving in any house of Congress, indicating the Members of Congress are not considered officers of the United States.20
Finally, congressional practice indicates that Members of Congress are not officers of the United States.21 In 1797, the House of Representatives voted to impeach Senator William Blount, the first impeachment in the history of the young Republic.22 Two years later, the Senate concluded that Senator Blount was not a civil officer subject to impeachment and voted to dismiss the articles because that body lacked jurisdiction over the matter.23 This determination has been accepted ever since by the House and the Senate, and since then, the House has never again voted to impeach a Member of Congress.24
https://www.law.cornell.edu/constitution-conan/article-2/section-4/offices-eligible-for-impeachment