The Constitution provides in Article 1, Section 3 paragraph 6 that when the President of the United States is tried "the Chief Justice shall preside" ...

There is NO AUTHORITY for Congress to decide IN  ANY WAY who shall preside over the impeachment of a President.  It is SPECIFICALLY provided that it MUST be the Chief Justice.

https://www.msn.com/en-us/news/politics/leahy-not-roberts-to-preside-over-impeachment-trial/ar-BB1d508P