I doesn't! The U. S. Constitution does not provide for overthrowing the election of a newly elected member just because the current members don't like who got elected to fill that seat!
@Bigun The Constitution Delegates (meaning the Constitution itself does not get involved) the Authority to Expel to "Each House"
What we'd be dealing with for Expulsion would be the Rules of the Senate
https://www.senate.gov/reference/index_sub_items/Expulsion_vrd.htm" Expulsion
Article I, Section 5, of the United States Constitution provides that "Each House [of Congress] may determine the Rules of its proceedings,
punish its members for disorderly behavior, and, with the concurrence of two-thirds, expel a member." Since 1789, the Senate has expelled only fifteen of its entire membership."
While not expounding on the ins and outs in great detail, it Appears to posit a proceeding founded upon the behavior of a Senator AS A Senator: Not his past life or accusations surrounding it.
And, as it it needed pointing out, 19 out of the 20 who Have been expelled from Congress were Democrats.
https://en.wikipedia.org/wiki/Expulsion_from_the_United_States_Congress"History of expulsions from Congress
In the entire history of the United States Congress, 20 Members have been expelled: 15 from the Senate and 5 from the House of Representatives (of those, 1 member's expulsion, William K. Sebastian of Arkansas, was posthumously reversed). 19 of the 20 expulsions involved a member of the Democratic Party, with the only exception pre-dating the founding of the modern political parties. Censure has been a much more common form of disciplinary action in Congress over the years, as it requires a much lower threshold of votes to impose."
Make of it what you will, but I don't seem to see being ACCUSED of dating high school girls ever having been considered sufficient grounds to Expel a New Senator.