When the Senate's so close you're bound to have trouble keeping your majority in line. Manchin kind of gets a pass because he represents such a red state. Sinema on the other hand represents a state that is considerably less conservative--if hardly liberal--and features another Senator, Mark Kelly, who is much more willing to play ball. So is Sinema being a savvy operator or really lagging behind where her state is politically?
If the latter, it doesn't seem like her positions are hurting her, at least not yet. Josh Kraushaar notes:
"A newly released poll conducted by OH Predictive Insights, conducted from Sept. 7-12, shows how unique her political coalition of support is in these tribal times. Her net favorability is plus-7 (46 percent favorable, 39 percent unfavorable) in a state that President Biden carried by a single point. While just 56 percent of Democrats view her favorably, she holds an above-water (plus-6) rating with independents and unusually high 40 percent favorability rating among Republicans.
All told, her overall favorability rating is a notch higher than newly elected Sen. Mark Kelly. He polls between 43 and 44 percent against all Republicans in next year’s Senate race. His net favorability rating is plus-4, with 47 percent viewing him favorably and 43 percent viewing him unfavorably."
That's consistent with the savvy operator idea. On the other hand, as Matt Yglesias points out, some of her specific objections to BBB are to items like prescription drug price bargaining, which is hugely popular in the country and most likely in Arizona as well. So you do have to wonder--she is probably more business friendly than she needs to be even for a state like Arizona. This may simply reflect her actual views on the policy desirability of being business-friendly, including in areas like this.
In all likelihood, her motivations in the current Congressional contretemps reflect a mix of both realpolitik and idiosyncratic, relatively conservative (for a Democrat) views. What's more certain is that Democrats desperately need her vote and will eventually have to compromise with her position and that of Manchin (and those of other, more conservative, Senators, who are hiding behind them).
Such are the wages of razor-thin Congressional majorities. With stronger majorities Democrats could compromise less. But that's not the situation yet. Sinema's not a demon, she's just a reflection of the Democrats' current weakness.