Independent Sen. Kyrsten Sinema of Arizona announced Tuesday that she won’t run for a second term after her estrangement from the Democratic Party left her politically homeless and without a clear path to reelection.

Sinema’s announcement comes after Senate Republicans blocked a bipartisan bill to help secure the border and deliver military aid to Ukraine and Israel, which Sinema spent months negotiating.

She’d hoped it would be a signature achievement addressing one of Washington’s most intractable challenges, as well as a powerful endorsement for her increasingly lonely view that cross-party dealmaking remains possible.

But in the end, Sinema’s border-security ambitions, and her career in the Senate, were swallowed by the partisanship common in Congress.

Flashback to 2022! Top Dem senator, often a deciding vote, leaves the party

The Associated Press contributed to this article.