The California Democratic Party signed a deal Tuesday to hold its endorsing convention in Long Beach this November—an event that could bring to town a parade of 18 presidential contenders.

California will play a pivotal role in choosing the person who will challenge President Donald Trump in 2020: Not only does the state send the largest share of delegates to the national convention, but it also moved up its primary next year to coincide with “Super Tuesday” on March 3, when at least 12 states will vote for the party’s presidential nominee.

The earlier primary forced the state Democratic party to hold two conventions in 2019 to prepare, party leaders said. The organizing convention will be held at the end of May in San Francisco, and the endorsing convention will be held Nov. 15-17 at the Long Beach Convention Center.

The fall event will bring some 5,000 visitors to Long Beach, including 3,600 delegates, about 1,000 honored guests, members of the media and others.

The party will also hold a third convention next spring, where it will formulate its platform, Executive Director Chris Myers said in a phone interview.

Though the state Democratic party does not endorse in national elections, Myers expects some or all of the 18 contenders for the presidential nomination to be pitching their candidacy at both the May event and the Long Beach convention. Those who have announced their candidacy include California Sen. Kamala Harris and U.S. Rep. Eric Swalwell, who represents a portion of the Bay Area.

The primary elections for 2020 will be held by each state between January and June, leading up to each party’s nominating convention in the summer.

In 2016, California held its primary in June, when both candidates for president—Hillary Clinton and Trump—had already secured the delegates needed for the nomination.

The earlier primary is expected to increase the power of California—a state that is home to nearly 8.5 million registered Democrats, by far the largest share in the country.