On Tuesday, President Joe Biden paid a visit to Arizona to tout not only the Inflation Reduction Act, but also announce his designation of the Ancestral Footprints of the Grand Canyon as a national monument. Sen Kyrsten Sinema (I-AZ) joined the president for his remarks, which might puzzle some since few people did more to stymie Biden’s agenda than Ms Sinema. Throughout his first two years, Ms Sinema expressed reservations — or more accurately stayed silent — as Democrats sought to craft their signature Build Back Better legislation that Senate Majority Leader Chuck Schumer and her buddy Sen Joe Manchin (D-WV) recrafted as the IRA.

Then, a year ago this week during the final votes for amendments, Ms Sinema sided with Republicans to support an amendment that nearly tanked the entire bill. Most notably, as Democrats sought to hold Arizona’s other Senate seat and flip the governorship, Ms Sinema remained on the sidelines before announcing in December that she would leave the Democratic Party to become an independent, though she still caucuses with Democrats for committee purposes. As a result, Rep Ruben Gallego (D-AZ), a decidedly more progressive Democrat, announced earlier this year that he would run against her. On top of that, friends of the Inside Washington Newsletter Hans Nichols and Juliegrace Brufke at Axiosreported that Kari Lake, the election-denying former Republican gubernatorial nominee, is preparing to jump into the race. The three-way race would create one of the most bizarre and most-watched Senate races in a must-win state for both Democrats and Republicans.

For years, Arizona was associated with a style of Western libertarian style conservatism. But Donald Trump accelerated Arizona’s leftward trend. Incidentally, Ms Sinema’s 2018 victory was the first sign Democrats could win in Arizona. Two years later, Biden won the state and Sen Mark Kelly won a special election to finish the late John McCain’s Senate term. Then in 2022, Mr Kelly won a full term while Katie Hobbs defeated Ms Lake despite the fact some polls showed the former news anchor-turned-top apologist for Trump leading. In the days before the election, Ms Lake specifically told “McCain Republicans” to “get the hell out” despite the fact he was the last Republican Senator to win in Arizona. Unsurprisingly, when she lost to Ms Hobbs, Ms Lake refused to concede and has instead become a darling of the right. Her bona fides with the pro-Trump right could easily boost her to become the nominee for Senate.

So far, Ms Sinema has elected, as she usually does on the Hill, to keep people guessing about her next step and has not indicated whether she will seek a second term in the Senate. As a result, Biden needs to keep Ms Sinema on his good side, lest she actually make the decision to defect to the Republican Party before 2024. But Ms Sinema choosing to run for another term might not unfold the way people might expect. A Noble Predictive Insights survey found that while Gallego has a 10-point lead in a head-to-head match-up with Ms Lake, Ms Lake and Ms Sinema would essentially have the same share of the vote while Mr Gallego would maintain a lead.

Of course, this would put Biden in a bind in a state he would need to win. Were he to get behind Gallego, he risks Ms Sinema running solely as a spoiler. Meanwhile, were he to abandon Mr Gallego or at least stay neutral, he risks alienating Democratic voters who he needs to turn out to keep Arizona in his column. Of course, were he and Ms Sinema to run and win, she could still prove to be a thorn in his legislative agenda as she has been in the past two years.