The Republican primaries will take place on Sunday in Washington, DC, where presidential contenders Donald Trump and Nikki Haley will face off.
Although it is a low-stakes race, it could represent one of Haley's best opportunities to achieve a victory over the former president.
Although the US capital only sends 19 of 2,429 delegates to the Republican National Convention in July, where the candidate is formally selected, the results of the DC primary could be significant. Reuters reported.
According to a senior official at the SFA Fund, the main super PAC supporting Haley's candidacy, D.C. could be unusually fertile territory for her.
Despite Trump's apparent advantage in previous nomination races, this race could be anyone's game.
It will be interesting to see how things develop on Sunday and what impact the results may have on the trajectory of the race.
The local party's only polling station in a downtown hotel has been open during the day since Friday morning and will close for the last time on Sunday at 7:00 p.m. (00:00 GMT), after which the vote count.
The city is 100% urban and a relatively high proportion of residents have a university degree. Trump's core base skews rural, and he is particularly strong in low-educated areas.
Haley campaigned in DC on Friday and hosted an event at the same hotel where the polling station is located.
The Trump campaign has been largely absent from the city, beyond sending text messages to local supporters asking them to vote.
The Democratic primaries in Washington will take place in June.
On Tuesday, voters in 15 states and one U.S. territory will gather or head to the polls on the biggest day of the presidential primary nomination contests. Known as Super Tuesday, 874 Republican delegates will be at stake.
