Kyrsten Sinema leaving Democratic Party to register as an independent
Kyrsten Sinema / Gage Skidmore.

The Democrats just lost one seat in their newly minted 51-49 majority in the U.S. Senate.

Sen. Kyrsten Sinema announced in an Arizona Republic column that she is leaving the Democratic Party and registering as an independent.

"Arizonans – including many registered as Democrats or Republicans – are eager for leaders who focus on common-sense solutions rather than party doctrine," Sinema wrote. "But if the loudest, most extreme voices continue to drive each party toward the fringes – and if party leaders stay more focused on energizing their bases than delivering for all Americans – these kinds of lasting legislative successes will become rarer."

Sinema insisted that Americans were more united than increasingly polarized political parties would have them believe, and she said that becoming an independent would allow her to better represent Arizona voters.

"Americans are told that we have only two choices – Democrat or Republican – and that we must subscribe wholesale to policy views the parties hold, views that have been pulled further and further toward the extremes," she wrote. :Most Arizonans believe this is a false choice, and when I ran for the U.S. House and the Senate, I promised Arizonans something different. I pledged to be independent and work with anyone to achieve lasting results. I committed I would not demonize people I disagreed with, engage in name-calling, or get distracted by political drama."