CHICAGO — Rep. Tom Suozzi, D-N.Y., who flipped a Republican-held district this year while calling for tougher border and asylum laws, was given a speaking slot Wednesday to amplify his message at the Democratic convention.

“Let’s be clear, the border is broken,” Suozzi told the crowd, before promising that Harris “joyfully accepts the challenge to work across party lines, to secure our border, to treat people like human beings.”

Moments later, Rep. Veronica Escobar, D-Texas, a pro-immigration progressive who represents a border district, echoed a part of his speech by slamming former President Donald Trump for convincing Republicans to kill a bipartisan bill that would have raised the bar for asylum and given the president new powers to shut down the border.

“With Kamala Harris as president, we can live up to the promise of America. We can strengthen legal pathways to immigration, we can secure our borders and we can treat with dignity those who seek a better future,” Escobar said.

The speeches made the border a major theme on Wednesday, solidifying a Democratic shift that began earlier this year on the explosive issue of migration in a bid to address what may be the party’s biggest political weakness.

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It’s a weakness that Trump has been hoping to ride to the White House, as his campaign hammers Harris as a failed “border czar,” referring to a diplomatic assignment the Biden White House gave her to address the “root causes” of migration from Central American countries. President Joe Biden issued an executive order to crack down on border crossings in June; the next month, illegal crossings fell to their lowest level since he took office in 2021.

After the Suozzi and Escobar speeches came a video touting the tough enforcement policies in the bill, including thousands of new border patrol agents and technologies to stop fentanyl. It included a clip of Trump embracing “blame” for the death of the bipartisan bill, which was co-written by Sens. James Lankford, R-Okla., Chris Murphy, D-Conn., and Kyrsten Sinema, I-Ariz. Most Republicans voted it down, saying it didn’t do enough to secure the border.

Trump “tanked” the bill “because he thought it would help him win an election,” Harris said in the video. “I went after transnational gangs, drug cartels and human traffickers that came into our country illegally,” she continued, referring to her tenure as attorney general of California. “I prosecuted them in case after case, and I won.”

Polling shows Harris’ border challenges

A recent CBS News poll from Aug. 14-16 highlighted the challenge for Harris. It found that voters who consider the U.S.-Mexico border as a major factor in their 2024 decision broke for Trump by a margin of 76%-24%. A plurality of registered voters believe that a Harris victory would “increase border crossings,” while a large majority said a Trump win would “decrease border crossings.” NBC News polling has also showed the border as one of Trump’s strongest issues in the 2024 campaign.

Democrats’ new emphasis in their message marks a stark contrast from 2020 and 2016, when the party spoke less about tougher law enforcement and spoke more about creating new legal pathways for people to immigrate. At the time, Democrats were heeding the advice of progressive and pro-immigration Hispanic advocates.

Neither Biden in 2020 nor Hillary Clinton in 2016 mentioned the border in their convention speeches. Clinton in 2016 vowed to “build a path to citizenship for millions of immigrants” who are already in the U.S., which has not been a recent focal point for Harris. Both Biden and Clinton had mentioned immigrants in the context of celebrating their contributions to the U.S. This year, Democrats are seeking to strike a balance by doing both.

During her failed 2020 presidential campaign, Harris also criticized the Obama administration for deporting record numbers of people in the U.S. illegally during his first term. “They should not be deported,” Harris said in a June 2019 NBC News debate. “This was one of the very few issues with which I disagreed with the administration.”

At the convention Wednesday, Murphy took the stage to depict Trump as an empty vessel using the border for politics.

“Trump killed that bill, and he did it because he knew that if we fixed the border, he’d lose his ability to divide us, his ability to fan the flames of fear,” Murphy said. “For 20 years, Kamala Harris has been tough as nails when it comes to securing our border.”

“We can be a nation of immigrants who love their country and a nation with a secure border,” he said. “There is only one candidate who can deliver that vision of America, and it’s Kamala Harris.”

The Democratic organization Blueprint has tested various messages on immigration and found that the Republican attacks on Harris as a “border czar” who has fueled “open-border policies” have resonance.

It also found that the best rebuttals include emphasizing Harris’ work as a prosecutor taking on gangs and drug smugglers, as well as her belief that immigrants should come here the legal way.

The group shared this advice with the Harris campaign this month and believes it is being reflected in the vice president’s response. One of the first TV ads of Harris’ campaign presented her as tough on border security, leaning on her work as a prosecutor. Biden never ran a border-themed TV spot during his re-election campaign, according to AdImpact.

“We’ve been thrilled to see these guideposts reflected in initial Harris messaging and ads on the border,” said Alyssa Cass, a Democratic strategist who worked on the Blueprint polling. “Suozzi on the podium seems to reflect a continued smart strategy from party leadership on Democratic messaging on the border.”