Until Vice-President Kamala Harris’s presidential campaign, most Democratic presidential contenders have treated immigration as a matter of legalising undocumented immigrants. They focused on “bringing people out of the shadows” and a “pathway to citizenship”. Harris, the former prosecutor, takes a different approach. She now treats illegal immigration as a law-enforcement issue at the border. In doing so, she helps move the party where it needs to go on the politics and policy of immigration.

Harris began her speech last week at the border with a tough statement of the type we have heard more often from Republicans than Democrats. “The United States is a sovereign nation. And I believe we have a duty to set rules at our border, and to enforce them,” she asserted. “I take that responsibility very seriously.” And then she noted that “we are also a nation of immigrants”.

The emphasis is on securing the border first — not as part of a comprehensive package, but as a necessity independent of what we must do to reform our legal immigration system and address the “dreamers”. Flipping the usual order for Democrats — which had been to talk first about dreamers, then the border — fits with her prosecutor persona, political reality and local communities’ immediate concerns.

Moreover, the concern for border security is bipartisan and reasonable. Unless and until the border can be effectively managed, many Americans will be hesitant to address any other aspect of immigration. (For this reason, the Senate Bill focused solely on border security.) Once the border is secure and an orderly process in place, the White House and Congress can turn to the slew of related issues, ranging from temporary agricultural workers to dreamers to high-skill workers brought in under H-1B visas.

Harris fully embraced the tough bipartisan immigration Bill in her remarks, delineating its provisions and laying blame at Donald Trump’s feet for nixing the deal. (“Donald Trump tanked it,” she said, bluntly. “He picked up the phone, called some friends in Congress, and said, ‘Stop the Bill.’ Because he prefers to run on a problem, instead of fixing a problem.”)

Throughout her address, and indeed throughout her campaign, Harris has leant into her work on the border as California’s attorney-general — eg, breaking up heroin trafficking, seizing cocaine from cartels, working with Mexico’s attorney-general, prosecuting human traffickers. She reiterated in Arizona:

"And I started the first comprehensive report in the state of California analysing transnational criminal organisations and the threats they posed to public safety and the economy. So stopping transnational crime and strengthening our border has been a longstanding priority of mine. I have done that work. And I will continue to treat it as a priority, when I am elected president.

Felon and former president Donald Trump has invented an immigrant crime wave and demonised and dehumanised immigrants. (They’ll cut your throats! They are poisoning our blood! They are eating your pets!) But the real crime problem, Harris knows, comes from those who exploit migrants and traffic in guns, drugs and human beings.

Her no-nonsense message conveys no concern for what the left flank of the Democratic Party may say. This is an election; they are fully behind her. She gets no pushback — pushback that at times plagued President Joe Biden’s attempts to respond to the border crisis — when she declares, “To reduce illegal border crossings, I will take further action to keep the border closed between ports of entry.” She continued, “Those who cross our borders unlawfully will be apprehended and removed. And barred from re-entering for five years. We will pursue more severe criminal charges against repeat violators. And if someone does not make an asylum request at a legal port of entry, and instead crosses our border unlawfully, they will be barred from receiving asylum.” Empathy for those fleeing desperate conditions does not mean our system cannot be “orderly and secure”.

Only near the end of her remarks did Harris reject “the false choice that suggests we must choose between securing our border or creating a system of immigration that is safe, orderly and humane.” Vowing to do both, she then affirmed the need for “clear, legal pathways for people seeking to come to our country”, speeding up the asylum process, working with Congress to legalise dreamers and addressing the need for agricultural workers.

Harris seems to be following the advice of centrist Democrats and think-tanks such as Third Way that urged Democrats in February to embrace the bipartisan deal and “and go on offence on immigration”. (Third Way polled the issue and found such an approach erased a 15-point advantage for Republican on immigration.)

As Jim Kessler, Third Way’s executive policy director, tweeted after Harris’s Arizona appearance, “For decades, immigration has been a vulnerability for Democrats. But Vice-President Kamala Harris is flipping the script and showing voters that she’s serious about restoring order at the border.”

Harris has been rewarded for her efforts with support from a group of existing and former Arizona Republican officials. On Sunday, former Arizona senator and former ambassador to Turkey Jeff Flake endorsed her as well. He welcomed a “tougher policy” on immigration. “She’s been a prosecutor. … She knows the problems of the border. So, I was glad to see her go down there,” he reiterated. He emphasised that the bipartisan Bill in the Senate would have been a welcome change in the asylum system.

Harris has made some inroads on immigration, according to polling. That might explain why Trump’s xenophobic rants have become more extreme and have turned his wrath towards even legal immigrants — eg, Haitians on temporary protected status. That is what desperation sounds like.

It bears mention: Harris is far from being the only Democrat to shift emphasis on immigration. Former Texas congressman Colin Allred is taking a similar approach in his Senate race against Ted Cruz, who has done nothing to solve the problem in 12 years in office, Allred argues. Allred also has embraced the bipartisan Bill. Citing his family’s roots in Brownsville, he takes the problems of local communities seriously.

If Democrats such as Harris and Allred succeed, it will be powerful evidence that Democrats can neutralise the issue on which Republicans have so heavily relied — and exploited — for decades.

• Jennifer Rubin writes reported opinion for The Washington Post. She is the author of Resistance: How Women Saved Democracy from Donald Trump and is host of the podcast Jen Rubin Green Room