DES MOINES — Since this past summer, Nancy Bobo has spent most of her waking hours trying to help Sen. Cory Booker win the presidency.

The veteran Democratic activist had knocked on as many as 200 doors a week, sometimes more, trying to drum up support for the senator from New Jersey. She spent her nights making phone calls, hundreds of them over the months, to friends and strangers, saying that Booker was the one who could beat President Trump, the one who could bring a divided nation together. Anything she could do, she did.

Bobo had come to know Booker’s personal story so well that she once jumped onstage at an event in the fall, taking the microphone away from the astonished candidate to deliver a more forceful pitch for his candidacy. “You’re just too modest,” she told Booker, who laughed.

She had stayed loyal through it all: the lousy poll numbers, the fundraising troubles. When Booker delivered a fiery speech here in December, decrying the party’s qualification rules that would block him from that month’s debate, she sat near the front, her face stricken with emotion at the senator’s soaring oratory and promises to lead with hope and love. “How can you listen to him and not be moved deep in your soul?” she said afterward.

On Jan. 13, less than a month before the Monday’s caucuses, Booker suspended his campaign for the Democratic nomination, citing money and the looming logistical issues of the impeachment trial. Booker, who was so personally close to Bobo that he had stayed at her house in Des Moines, called her that morning, thanking her for her support and urging her to fight on, to look for another contender to support. And Bobo agreed, but what do you do when you fall in love with a candidate who doesn’t go the distance?

“It’s been a tough couple of weeks for me,” Bobo said Friday, on the eve of the final weekend before the caucuses. “I continue to pay attention. I’ve gone to a few events. I do know the need to elect a Democratic president in November. My spirit just isn’t there. … The wind is out of my sail.”

For the first time in three decades, Bobo wouldn’t be serving as a precinct captain for a candidate at her local caucus. She wasn’t caught up in the last-minute frenzy of getting all of her candidate’s supporters in place. Earlier in the day, an organizer had knocked on her door, and she opened it and stood there for a while, thanking him for the hard work he was doing but feeling sad she wasn’t out there, too. “I wish I were out there for Cory today,” she told him.

Instead, she was getting ready to go run some errands, trying to fill all the extra time she suddenly had on her hands. She had caught up with friends and had more time to spend with her grandkids, but she felt empty. “I hadn’t realized how much of my life was wrapped up in the campaign until it was over,” she said. “It’s a pretty weird sensation, not being crazy busy in the days leading up to [caucuses]. It’s a very odd feeling for someone like me.”

Bobo has loved candidates before. During the 2008 campaign, she was one of the earliest Iowans to endorse Barack Obama, back when many Democrats here questioned whether the senator from Illinois was too young, too inexperienced for the presidency. Inside her home, she had a cardboard cutout of herself and Obama, and recently, aides affiliated with his presidential library had come to collect some of the memorabilia from that history-making campaign.

But as personally close as she became with Obama, Bobo felt even closer to Booker, as if he had become a part of her family. She recalled the long conversations they’d had when he was a guest in her home, many of them going late into the night. Bobo, who is white, married her husband, Melvin, who is black, in 1973, back when being an interracial couple in majority-white Iowa wasn’t easy. She recalled how Booker had walked around her kitchen staring at their family photos and asking her and her husband to talk about what they’d been through. At one point, Booker wiped away tears. “That is true love,” he told her.

Within hours of Booker ending his campaign, Bobo’s phone began to ring. The calls were from other campaigns, asking her to come to their events, pressing her to consider backing their candidates. Bobo, who was still trying to process her candidate’s exit, found the appeals tacky and off-putting. “I know where it was coming from, but I was like, come on, give me some time,” she said. “Respect the space.”

One morning later that week, Bobo opened her front door and found a bouquet of flowers on her doorstep with a note. It was from Joe Biden’s campaign, expressing sympathy that Booker had exited the race. “It was nice and noninvasive,” she said.

Bobo knew Team Biden well. She had considered endorsing the former vice president last year. She’d known him from the Obama years. And last spring, when they met face to face, Biden asked for her support. Bobo had been on board with him, until she met Booker.

A few days later, she got a call from Biden’s niece Missy who apologized if she was calling too soon. “I understand what you’re dealing with,” Missy Biden told her. A few days later, she and five other women were invited to have a glass of wine with Jill Biden, the candidate’s wife.

By then, Bobo had already decided she would caucus for Biden. “I like Joe. I’ve always liked Joe. I have this familiarity with Joe that I’ve had for a long time. … I think he’s just a really decent man,” she said.

But he’s not Booker. On Monday night, Bobo will be at her local caucus, working as a volunteer, helping to sign people in and doing whatever she can to help it run smoothly. That had been one of Booker’s requests of his team when he ended the campaign. Many of his Iowa field staffers stuck around to help the local parties, which have struggled to find volunteers amid predictions of record-breaking turnout.

Bobo plans to wear her “Booker for President” sweatshirt. And like other Booker supporters, she plans to stand for the senator from New Jersey in the caucus’s first alignment, to show her support for the candidate she loved from the beginning and who she wishes were still in the race. “I want to register my support for Cory. He certainly deserves it,” Bobo said. “And then I will move over to Joe Biden.”

She admits having mixed feelings going into caucus night — a day she had been working toward for months, a day that has been so important for most of her adult life. “It’s weird not to feel excited about caucus night,” she said. “I’ll be there, but I don’t have the thrill I usually do.”