I had assumed there was some significance to Bernie Sanders becoming the Chair of the Budget Committee, but it appears to be an automatic assignment rather than a choice by the incoming administration.
What determines who becomes the chair of which Senate committee?
Each party in the Senate has their own rules in determining committee assignments and appointments of the top member on committees. The Democrats rely largely on seniority in appointing committee leadership.
Democratic senators also voted to reject a six-year limit on committee leadership posts, preserving the caucus’s long-standing seniority system, while also placing restrictions on the committee postings for the top two leaders, the officials said.
Bernie Sanders has served as the ranking member1 (i.e. top Democrat) on the Senate Budget Committee since 2015. As the Democrats took control of the Senate this week, he will become the chairman of the committee.
With regards to how Sanders became the ranking member on the Budget Committee, from The Hill:
In one of the more interesting moves, Sen. Bernie Sanders (I-Vt.) will become the ranking member on the Senate Budget Committee.
Sanders is moving into the slot because Sen. Patty Murray (D-Wash.) opted to take top Democrat's job on the Senate Health, Education, Labor and Pensions (HELP) Committee.
1Defined on the Senate's website as "The highest ranking (and usually longest serving) minority member of a committee or subcommittee."
What determines who becomes the chair of which Senate committee?
From Senate Committees —
The Role of Seniority in Selection of Chairmen and Ranking Members
Traditionally, the majority party member with the greatest seniority on a particular committee serves as its chairman. When the Republican Party gained the majority in 1995, it altered its conference rules to allow Republicans on individual committees to vote by secret ballot for their committee's chairman, irrespective of that member's seniority. This adjustment was a logical consequence of the party's larger decision to place a six-year term limit on the service of its chairmen or, when in the minority, its ranking members.
