Though he dominates political talk on cable news, President Trump was not the main subject of Wednesday night’s Democratic debate — instead, the candidates sparred primarily on immigration, health care, and climate change. Midway through, Trump issued his verdict on Twitter: “BORING!”

Julian Castro, the former secretary of the Department of Housing and Urban Development, set the tone on the immigration debate. He has advocated decriminalizing crossing the U.S. border, and instead making it a civil penalty. He noted the deaths of Oscar Alberto Martinez Ramirez and his daughter Valeria, who drowned Sunday trying to cross the Rio Grande, and argued that his plans would have spared their lives.

He also challenged his fellow Texan, former Rep. Beto O’Rourke, for not supporting his decriminalization proposal.

“I think you should do your homework on this issue,” Castro said.

Castro, O’Rourke, and Sen. Cory Booker each gave some answers in Spanish. In his closing, Castro said, “On Jan. 20, 2021, we will say ‘adios’ to Donald Trump.”

As the subject turned to gun control, the NBC moderators struggled to deal with a feedback issue with the microphones. Chuck Todd threw to a commercial break, which lasted several minutes as the issue was sorted out.

Sen. Elizabeth Warren, who is polling third nationally, was the leading candidate on stage on Wednesday. The second debate, on Thursday, will feature frontrunners Joe Biden and Sen. Bernie Sanders, as well as Sen. Kamala Harris and Mayor Pete Buttigieg.

Warren got ample opportunity to tout her support for Medicare for All, and her plans to address wealth inequality. Though Sen. Amy Klobuchar and others made oblique criticisms of her proposals, no one launched a full-scale attack on Warren.

Klobuchar presented herself as a pragmatic alternative, saying she would not make big promises. On health care, she said she supports a public option as the best path to universal coverage, and opposed a plan advanced by Warren and others to do away with private insurance.

“I’m concerned about kicking half of America off their health insurance in four years,” Klobuchar said.

In response, Warren said it was a mistake for candidates to set low expectations.

“What they’re really telling you they just won’t fight for it,” she said. “Health care is a basic human right and I will fight for basic human rights.”

The candidates gave a wide range of answers when asked the top threat to the United States. O’Rourke and Warren cited climate change, while Rep. Tim Ryan cited China. Klobuchar noted the situation in Iran, and Mayor Bill de Blasio cited Russia.

“The biggest threat to the security of the United States is Donald Trump,” said Gov. Jay Inslee, winning significant applause.

Earlier, Inslee argued that climate change should be the country’s top priority.

“We are the first generation to feel the sting of climate change and we are the last that can do something about it,” he said. “This is our last chance.”

De Blasio interrupted several times throughout the evening, looking for openings to get off a memorable line. The New York mayor said it was time for Democrats to “stop acting like the party of elites.” On immigration, he said it was important to tell working people who feel left behind by the economy.

“The immigrants didn’t do that to you, the big corporations did that to you,” de Blasio said. “The 1% did that to you.”