Well, to put it simply, she violates a lot of norms.
She will not negotiate on Biden’s most important legislation. She jets off to Paris while her party experiences a legislative crisis. She fundraises and runs marathons when she should be working. She upholds the filibuster. She won’t talk with her supporters. She dresses like a tart, offending effete Washington standards. She wears a ring that says “Fuck off.”
One could go on, but the media have covered all of this. Let me offer some cheap analysis.
Sinema seems drunk with the power of her position. She has the pride of a person with no fixed values, like a character out of Dostoevsky. This can only end badly. Republicans like McConnell profess to love her, while progressives are organizing against her. Politically she has burned her bridges.
She and Joe Manchin, another egotist, may well torpedo the Biden agenda approved by a majority of the public. That might just end their political careers. Party loyalty has now been transformed into partisanship, and partisans brook no apostasy. A Yale study “found that just 3.5% of respondents would vote against their partisan interests to protect democratic principles.” Biden’s unforced errors won’t torpedo his program, but partisanship surely could.
If she continues to offend Democratic (and indeed democratic) values, Sinema will either have to become an Independent or find a new career as a lobbyist. She seems to be positioning for the latter. In 2003 she ran a campaign against the hawkish and waspish Joe Lieberman. Now she’s become a Lieberman and he defends her.
Sinema appears to have become a product of her own periodic whims, which is maybe why she refuses to explain herself. She’s in danger of becoming a rebel without a cause.