FORT MADISON, Iowa (AP) — The Iowa caucuses could feature an attack of the "zombie" candidates.

As some Democrats prepare for Monday's contest, they say they're planning to side with candidates who have been out of the race for weeks, even months. By caucusing for Sens. Kamala Harris of California and Cory Booker of New Jersey, voters say they want to establish a record that those who bowed out early did indeed have supporters.

"I really still feel that for me, Cory Booker's the right person to be the president," said Bryce Smith, the Dallas County Democratic Party chairman who had endorsed Booker and was organizing for him in his precinct. "I think it sends a clear message that Cory was important in this race.

Such tactics reflect the unique and complicated nature of the caucuses.

In a primary, voters simply choose their preferred candidate. Caucuses require strangers and neighbors to spend a winter evening in high school gyms or community centers. Participants first line up for their favored candidate. If that candidate doesn't receive more than 15% of the vote in the room, the candidate is eliminated and supporters can align with one of the remaining White House hopefuls.

The results are counted again. Delegates are awarded based on that final number.

The caucuses have an added twist this year because the Iowa Democratic Party will release more data than ever. While the party previously only released information on delegates, it will now report the first round of voting, the second vote "realignment" and the final delegate count.

The Associated Press will base its race call of the winner on state delegate equivalents because delegates are the measure used to decide the eventual winner of the nomination. But the new information is causing some voters to take their first round choices more seriously because those decisions will now be public.

Ruby Bodeker said she and her 17-year-old daughter both plan to caucus for Harris during the first round.

"This is her first caucus," Bodeker said of her daughter. "She was devastated when Kamala Harris dropped out. As a member of the LBGTQ+ community she feels there is no one left who speaks to her."

Caucus goers can theoretically support whomever they like on the first round, so any of the other candidates who have dropped out could receive votes as well.

Some voters said they'll caucus for a former candidate to eat into whatever advantage Vermont Sen. Bernie Sanders hopes to build during the initial round of voting. Sanders, a self-described democratic socialist, and his team have said they want to win each category of voting, but have placed special emphasis on the first round.

Helen Grunewald, a 69-year-old retired community college teacher who will serve as her precinct caucus chairwoman in Blairstown, said after Harris quit the race, she couldn't find any other candidates that she cared about. The only candidate who drew her passion was Sanders, who she opposes.

"Since I didn't feel strongly about any of the candidates, and the only one I feel strongly about is the one I don't want to get it, figured the thing to do is to stick with Kamala," she said.

Grunewald doesn't expect Harris to win the 15% support she'd need to be viable on the first alignment, so she plans to support whichever candidate looks the strongest against Sanders on the second alignment.

Smith, the county chairman, also expressed concerns about Sanders' strength in the race, as did Gary Dickey, a Des Moines-area lawyer and former aide to former Iowa Gov. Tom Vilsack, who endorsed Booker. Dickey tweeted he plans to caucus for Booker on the first alignment and said he's heard from numerous people in response that are considering doing the same thing.

He and his wife like former South Bend, Indiana, mayor Pete Buttigieg, Massachusetts Sen. Elizabeth Warren and former Vice President Joe Biden and said they will support whichever one is stronger against Sanders on the second alignment.

"We are both very concerned that if Bernie Sanders were to win Iowa and New Hampshire and get some momentum, we don't think that's good for the party, and we don't think it'd be good for Democrats in a general election," he said. "I worry that an admitted democratic socialist creates headwinds that would make the general election unnecessarily difficult."