The three Democratic presidential candidates appeared at a forum in Des Moines tonight as polls show the contest between Vermont Senator Bernie Sanders and former Secretary of State Hillary Clinton tightening in Iowa.

“Have you noticed maybe that she’s been getting more aggressive with you?” one of the event’s hosts asked.

Sanders, the first of the three to spend half an hour on stage, smiled and said: “Yes…I don’t know. It could be that the inevitable candidate for the Democratic nomination may not be so inevitable today.”

Sanders and Clinton have been sparring over gun issues and Sanders was asked about his vote for a bill that shields gun makers and retailers from liability lawsuits.

“Did you make a mistake?” a moderator asked.

“No,” Sanders replied. “Like many pieces of legislation, like many of the 10,000 votes that I’ve cast, bills are complicated.”

Sanders said he’d take a “new look” at that legislation, though, and allow lawsuits for targeting gun sales to “criminal elements.”

Both Sanders and Clinton support a law giving Americans three months of paid family and medical leave. Sanders would pay for it with a new payroll tax and he accuses Clinton of offering a “vague” way to pay for it.

“That’s interesting because I have laid out, specifically, my tax plans,” Clinton said when pressed on the issue. “And my friend, Senator Sanders, has said that he will lay his out before the Iowa Caucus and I and others will be anxious to see them.”

Tonight’s “Iowa Brown and Black Forum” was billed as an event to press the candidates to address issues minority voters consider important. Clinton called on the Obama Administration to stop immigration raids seeking undocumented Central Americans in the U.S.

“I do not think the raids are an appropriate tool to enforce the immigration laws,” Clinton said. “In fact, I think they are divisive. They are sowing discord and fear.”

Martin O’Malley, the former governor of Maryland, was quizzed about the percentage of minorities on his campaign staff and asked whether America’s schools are in “a state of apartheid.”

“Unlike Governor Branstad who cuts public education, I increased public education funding by 37 percent,” O’Malley said, drawing applause from the audience.

O’Malley told the crowd he was first among the candidates to embrace refugees from Central America and to call for ending immigrant detention camps.

“Sometimes people say to me: ‘Are you to the left or the right of your opponents?’ Actually, I’m to the forward of them,” O’Malley said. “I arrive at things before they do.”

The event was broadcast on the Fusion Network, which is a joint venture of ABC and Univision.