If it seems like the 2020 election has been going on for a while, you’re right.

But on Monday, Feb. 3, voters make their first big choice when Iowa Democrats caucus in the nation’s first electoral contest in a presidential election year like no other.

The caucuses are the Democratic Party’s first nominating contest in the 2020 presidential election. The caucuses, which will be held during the evening, are closed, and candidates must meet a viability threshold of 15% within an individual precinct in order to be considered viable.

Former Vice President Joe Biden, U.S. Sens. Bernie Sanders and Elizabeth Warren; and South Bend, Indiana, Mayor Pete Buttigieg are hoping for an outright Iowa victory. Lower-tier candidates such as Andrew Yang, U.S. Sen. Amy Klobuchar, and U.S. Rep. Tulsi Gabbard believe an Iowa surge could propel them into top contention.

What’s a caucus?

Unlike a traditional primary, in which voters cast ballots, caucuses take place out in the open. People show up to their precinct and physically move into designated parts of a room to show their preference for a certain candidate. Delegates are awarded based on those who reaches a certain threshold of support by the end of the night.

How does it work?

Republican caucuses will be straightforward, confirming President Donald Trump as their party’s candidate. For Democrats, participants physically divide themselves into their candidates’ groups. This is called the first allocation, and it determines which candidates are viable. Those failing to make the threshold — set at 15% to 25%, depending on precinct size — must then try to win enough new members to keep their candidate viable, join some other candidate’s caucus, become uncommitted, or simply go home.

»MORE: Here’s why Iowa caucuses are so important

Following this one and only round of shuffling, a final allocation tally is taken to determine the number of delegates sent to later county conventions. The "state delegate equivalent" results is is used to calculate the number of national delegates each candidate receives; those delegates will go to the national convention.

A Democratic candidate needs 1,991 pledged delegate votes to win the party's nomination on the first ballot of the convention.

When does it begin?

At 8 p.m. EST.

What’s different this year? 

Iowa’s Democratic Party is adding several satellite caucuses in nursing homes and union halls in an effort to increase participation. Some of those caucuses are even taking place for Iowans out of state and for Hawkeye state expatriates in cities around the world.

Why is Iowa such a big deal?

It’s the first state to vote in an election that only happens every four years: the presidential one. And even if Iowa doesn’t always pick White House winners (since 1971, only Jimmy Carter, George W. Bush and Barack Obama won Iowa and the White House) it does eliminate losers.

»Dates you should know for Election 2020

The old axiom that “there are three tickets out of Iowa” means the top three finishers have the best chance of remaining in the race and making their way to New Hampshire on Feb. 11; the Nevada caucuses on Feb. 22; the South Carolina primary on Feb. 29; and then Super Tuesday on March 3.

So who’s the favorite?

That’s the big unknown. Sanders, Warren and Klobuchar have been forced back to the Capitol for Trump’s impeachment trial, leaving their campaigns in the hands of their managers and surrogates.

After the brief Saturday Senate impeachment session, several candidates roared back into Iowa on Saturday touting fresh endorsements, critiquing their rivals and predicting victories.

A New York Times/Siena College poll released Saturday showed Sanders with a slight edge in Iowa. But several polls show Biden, Buttigieg and Warren remain among the front-runners. Other polls suggest Biden also has a substantial appeal among Democratic voters, especially African Americans.