Senator Kyrsten Sinema (AZ) changed her voting registration in Arizona today from “Democrat” to “Independent” and said she will no longer consider herself a member of the Democratic Party. However, she made clear that she will continue to affiliate with Senate Democrats, just like the two other independents, Bernie Sanders (I-VT) and Angus King (I-ME) do, and thus hoped to keep her assignments to the Commerce, Science and Transportation Committee, the Banking, Housing, and Urban Affairs Committee, and the Homeland Security and Governmental Affairs Committee out of the Democratic majority allotment.

This matters for transportation because Sinema is currently the chairman of the Aviation Subcommittee of the Commerce panel, and if she retains that post in the upcoming Congress, she will hold practical veto power on the aviation policy reauthorization bill that Commerce will consider next year. (That is, she will hold practical veto power if Commerce drafts a bill in the traditional “Big Four” bipartisan manner, but since Ted Cruz (R-TX) is taking over the head Republican slot on Commerce, and Cruz has voted against bipartisan Big Four legislation in Commerce in the past, we’re not sure how next year will shake out.)

Sinema’s decision won’t change the balance of power in Washington. Her switch is all about Arizona politics – as long as she stayed a Democrat, she was subject to a fierce challenge in the Democratic primary from progressive Rep. Ruben Gallego (D-AZ). But if she runs for Senate as an independent, the more progressive the Democratic nominee is, the more centrist Sinema looks. Sinema is also clearly counting on Republicans to nominate another Trump-endorsed MAGA candidate and trying to draw as many votes as possible from centrists in both parties.

After a morning of uncertainty regarding Sinema’s committee assignments, Majority Leader Chuck Schumer (R-NY) released this statement at mid-day:

Senator Sinema informed me of her decision to change her affiliation to Independent. She asked me to keep her committee assignments and I agreed. Kyrsten is independent; that’s how she’s always been. I believe she’s a good and effective Senator and am looking forward to a productive session in the new Democratic majority Senate. We will maintain our new majority on committees, exercise our subpoena power, and be able to clear nominees without discharge votes.

That last sentence in Schumer’s statement is the difference between a 50-50 Senate and a real majority (currently 51 seats) – under the 50-50 power-sharing agreement, each party had an equal number of seats on each committee, chairmen could not issue subpoenas without minority permission, and each bill or nominee that failed on a tie vote in committee had to be subject to a special, time-consuming discharge motion on the Senate floor.

So we can be certain that Sinema will keep her assignment to Commerce and the other two panels (unless she somehow gets promoted to Appropriations or Finance, but she’s still not quite guaranteed to keep the Aviation Subcommittee. Sinema is only the 10th most senior Democrat on Commerce. Here is a list of the current 14  Democratic members and the Commerce subcommittees they chair, if any:

We are not sure what would happen if, for example, Tammy Baldwin (D-WI) decided that she preferred Aviation to Oceans in a reuthorization year, or whether or not Tammy Duckworth (D-IL) were to decide that O’Hare needs her at Aviation next year more than the state needs her chairing the Clean Water subcommittee at EPW. Maybe Sinema gets bumped and has to choose another subcommittee. But the possibility for her to chair Aviation next year remains, even though she will no longer, technically, be a Democrat.