JOHNSTON, Iowa — For weeks undecided Iowans have been saying that they may make their decision based on the last candidate they see in person. On Monday night, that sentiment paid off for Senator Amy Klobuchar of Minnesota at Johnston Middle School.

The senator was a surprise guest at the Johnston 2 precinct, popping in just after the caucus began to make one final pitch to the more than 350 attendees.

“The most important thing is that we win in the general election,” she said, adding that if she was the nominee, the party would rebuild the “blue wall” that President Trump had cracked in Michigan, Pennsylvania and Wisconsin in 2016. “We’ll make Donald Trump pay for it,” she added.

While the final results were unclear, there was no shortage of drama inside the middle school gymnasium, where each of the campaigns staked out room on the yellow bleachers. A handful of undecided Democrats were swarmed by the precinct captains of the most competitive campaigns, who were charged with lobbying people to back their candidate.