I don’t get this. Why would she give up now unless she immediately takes another job and couldn’t wait.
Absolutely standard for Commission Chairs to resign with a change in White House party. The rule for the regulatory commissions is that they have 3 members of the President’s party and 2 members of the other Party, and the President chooses one of his own Party’s members to be Chairman. The resignation avoids the indignity of being a mere Commissioner after having been Chair, and also permits the President immediately to have a majority from his Party on the Commission. The FCC, CFTC, NRC, STB and FTC Chairs will all announce their resignations shortly, under the same principal. The Federal Election Commission and Civil Rights Commission run by different rules and traditions.