Thousands of Iowans will caucus on Monday starting at 7 p.m. at more than 1,600 sites across the state to pick their preferred Democratic presidential candidate. Iowa is the first state in the nation to vote, kicking off the official start of the 2020 presidential elections.

The caucuses vary in length, but the results are expected to begin rolling in at 8:30 p.m. ET, with most results secured by 11 p.m.

Seven Democratic candidates are leading the pack in Iowa: Sen. Bernie Sanders (I-VT), former Vice President Joe Biden, Sen. Elizabeth Warren (D-MA), former Mayor Pete Buttigieg of South Bend, Indiana, Sen. Amy Klobuchar (D-MN), former tech executive Andrew Yang, and billionaire Tom Steyer. Republican caucuses will also take place on Monday, which President Donald Trump is expected to win.

Iowa has 41 pledged delegates this year, which is just a fraction of the 1,991 delegates a candidate needs to win the party’s presidential nomination. The results will ultimately determine which candidate is “viable” and has enough momentum in the race.

Democratic caucus attendees will move around a caucus location and assemble in designated groups at the site to show support for a candidate.

If a candidate does not garner 15 percent of support from attendees at their caucus location, they do not meet the “viability threshold.” Attendees will then either have to choose another candidate or their vote will not count—a process called “realignment.”

The number of winning delegates at each site is determined by a mathematical formula.

The Democratic party will release three sets of results at the same time: the first expression of preference, the final expression of preference, and the final expression number, which will determine who gets delegates.

How to watch results: