MARSHALLTOWN — Vermont Senator Bernie Sanders Thursday called campaign spending by outside groups “an outrage.”

“I don’t need a ‘Super PAC.’ I am not going to be controlled by a handful of wealthy people,” Sanders said in Marshalltown. “I will be controlled by the working people of this country.”

Sanders made the statement after former Vice President Joe Biden’s campaign signaled Biden was now open to “Super PAC” support of his candidacy. Sanders, who was asked about the issue during a town hall forum in Marshalltown, said Super PACs are “corrupting” America’s political system.

“It is an outrage and you read it in the papers every day. An article in The New York Times the other day: ‘A group of donors said A, B, and C.’ Who the hell cares what a group of rich donors say?” Sanders asked, to cheers from the crowd.

Sanders said those donors are upset that he has raised far more than Biden in small donations from over a million Americans.

Thursday evening, Sanders was one of three presidential candidates to speak in Des Moines at a forum sponsored by LULAC — the League of United Latino Citizens. Former San Antonio Mayor Julian Castro told the audience his party has become wary of the immigration issue because of President Trump.

“I wish that these Democrats would stop speaking like Republicans,” Castro said, to cheers.

Castro supports a pathway to citizenship for people who entered the country illegally. He would also change the law so illegally crossing the border would be a civil rather than criminal offense.

“We’re going to have an immigration system that is orderly and reasonable and, of course, we’re going to keep our borders secure, but we’re going to treat people with common sense and compassion,” Castro said. “And we’re also going to be more thoughtful with a 21st century ‘Marshall Plan’ for Honduras, El Salvador and Guatemala, so that people can find safety and opportunity at home instead of trying to make a dangerous journey to the United States.”

Former Texas Congressman Beto O’Rourke talked about the mass shooting in his hometown and his call for banning assault-style guns.

“An AK-47, that was the weapon that was used in El Paso, that should not be in civilian hands and it’s not just me saying that. It’s veterans who have used those weapons who say that,” O’Rourke said, to applause.

O’Rourke also mentioned his support of universal background checks and so-called “red flag” laws that let authorities take guns from people if there’s a concern they may harm themselves or others.

“I don’t want to do anything to infringe on your Second Amendment right, but there is no right to own a weapon of war,” O’Rourke said. “We wouldn’t allow you to have a bazooka or to drive a tank down the streets because those rightly belong on the battlefield and do not belong in our communities.”

Hawaii Congresswoman Tulsi Gabbard had been scheduled to attend the forum, which was broadcast by Newsmax-TV, but she was unable to be in Des Moines, so she recorded a video that was played for the crowd and during on the two-hour-long broadcast.