Burgess Everett explains at Politico why one Democratic U.S. senator might frustrate progressive colleagues on a continuing basis.

Kyrsten Sinema doesn’t often make big policy pronouncements. But when she does, Democrats had better listen.

Take the $15 hourly minimum wage that Democratic leaders want to add to a $1.9 trillion coronavirus relief package. Sinema, who became the first Democrat to win a Senate race in once deep-red Arizona in 30 years, is crystal clear: She’s against including it.

“What’s important is whether or not it’s directly related to short-term Covid relief. And if it’s not, then I am not going to support it in this legislation,” Sinema said in a telephone interview this week. “The minimum wage provision is not appropriate for the reconciliation process. It is not a budget item. And it shouldn’t be in there.”

Sinema’s opposition is a blow to Democrats’ hopes of bumping up the federal minimum wage through budget reconciliation to avoid a GOP filibuster, complicating follow-through on a campaign promise from Democrats and President Joe Biden. And her defense of the Senate’s age-old rules is likely to frustrate progressives eager to use every tool at their disposal to advance their priorities in a Senate where one wayward Democrat can mean the difference between a policy breakthrough and utter failure.

Her breaks with her liberal colleagues are both a reflection of her state, which she won by a narrow margin in 2018, and her temperament. But the former state legislator, House member and now first-term senator has literally never served in the majority before — so she feels the minority’s pain.

It’s just one of the things that makes the 44-year-old Democrat one of the most quirky and interesting members of the stodgy Senate. …

… And though she’s more attentive to Democratic Caucus meetings than she was in the minority, she still keeps Republicans at least as close as members of her own party.