Scott Jennings, a CNN contributor, is a former special assistant to President George W. Bush and former campaign adviser to Sen. Mitch McConnell. He is a partner at RunSwitch Public Relations in Louisville, Kentucky. Follow him on Twitter @ScottJenningsKY . The opinions expressed in this commentary are his own.

(CNN) Two dumb things happened in the last several days: The Trump administration separated children from their parents as they, many of them illegally, crossed the border into the United States, and the American left assumed that the subsequent outcry over this decision would fundamentally alter the political landscape.

This flap over family detention has again laid bare a debate that worked in Trump's favor in 2016 and could still help him and the Republican Party win in 2018 and 2020: One party prefers tighter immigration restrictions and one party leans toward relaxed enforcement. Trump himself made that case in a speech in Las Vegas over the weekend, when he cited in fiery terms Democrats' desire for "open borders" on a campaign swing designed to boost the fortunes of incumbent Republican Dean Heller.

Democrats are likely to be disappointed when they poll this issue. My guess is that a majority of Americans will feel the same about Trump before and after, and some may even like him more. The bottom is not going to fall out of this presidency over Trump taking a position that conforms with his hardline anti-immigration stance. I imagine a negligible number of Trump supporters will abandon their support for him over this misguided policy.

Regarding what to do with the immigrant families once they are detained, Democrats should not assume wide support for the position taken by Sen. Kamala Harris of California -- essentially, release them inside the United States pending a hearing. While most polling shows that Americans view legal immigration as a positive thing for the United States, a sizable portion of Americans would likely prefer to keep the families together before deporting them to their country of origin -- as opposed to releasing them inside the United States. Most voters welcome people coming here legally, but believe illegal immigration is a serious problem.

Being candid about Trump's decision to engage in a policy leading to family separation, surely the White House wishes it could have that one back. The President wound up reversing course via executive order after days of painful images and audio recordings created a public outcry. Shifting explanations from various administration officials made the position untenable, and the President smartly put an end to it last Wednesday, although Trump can take solace in former Department of Homeland Security Director Jeh Johnson's admission on Fox News on Sunday that the Obama administration did, in fact, detain some children alone.

As for the Democrats, they couldn't take yes for an answer. After clamoring for the President to end his administration's policy, they moved the goalposts as soon as he did. What started as a demand to stop separating families has morphed into a call to stop detaining the families altogether.

Harris, a possible 2020 presidential candidate tweeted that "Indefinitely detaining children with their families in camps is inhumane and will not make us safe." In other words, she wants the families caught and released into the United States. She went further , asking other senators to support her "DONE Act to prohibit the expansion or construction of new detention facilities."

Where are we supposed to put the people caught illegally passing into the United States if we don't have enough detention facilities? The answer, of course, is nowhere. Harris doesn't seem to want them detained at all.

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While President Trump was wrong to move to the harsh penalty of separating children from their families, Democrats are playing with fire by putting catch-and-release at the top of their agenda. Americans clearly believe we need stronger borders, even as they prefer the families be kept together before being shipped home.

Left-wing political and media figures are playing into the President's hand by trying to delegitimize his concerns about criminals crossing our borders. On "CNN Tonight" last week, responding to a point I made about the President's preference that we stop violent criminals at the border, New York Times columnist Charles Blow said : "We wouldn't have a country if it wasn't flooded with criminals in the very beginning."

While Blow isn't wrong that some criminals were sent here from England in the 1700s (before we were an independent nation, by the way), I'd like to see a congressional candidate use that as a rationale for a position of catch-and-release in the fall election. Good luck!

Beyond that, whatever Trump's family separation position cost the Republican Party politically has more than been erased by hysterical comments like those from Democrats like Rep. Maxine Waters, who called for the public to "create a crowd" to "push back on" Trump administration officials. She included a startling call to action : "If you see anybody from that Cabinet in a restaurant, in a department store, at a gasoline station, you get out and you create a crowd. You push back on them. Tell them they're not welcome anymore, anywhere!" Her remarks followed incidents of harassment targeted at Trump's press secretary Sarah Sanders and Florida Attorney General Pam Bondi , who were run out of public places.

Americans across the political spectrum can have reasonable — even fierce — policy disagreements, but calling for angry mobs to hound political enemies will strike most Americans as dangerous. House Minority Leader Nancy Pelosi referred to Waters' comments in a tweet as "unacceptable," but also blamed Trump's "lack of civility" as a provoking factor. The fact is that voters may not want to trust control of the government to people who believe in mob justice over civil discourse.

But while the outcry over immigration policy isn't likely to doom the GOP's chances at winning, Republicans still have work to do.

More optimistic rhetoric and party unity would be helpful. Imagine if congressional Republicans could unify around legislation that did it all — secured the borders, saved the Dreamers, unified families and reformed a broken system. GOP unity would force the Senate Democrats to provide 10 votes for a big fix or face backlash for obstructionism. Alas, the GOP currently remains fractured on broad solutions.

I would also advise Republicans to embrace the reason immigrants are coming here: We have a country that is worth the risk. As long as we have more jobs than people to fill them ( we do ), and as long as America is safer than the violent villages of Central America ( it is ), we can expect people to continue to risk it all to come to the United States.

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This is not a bad thing. It means that under President Trump and the Republicans, our economy is red hot and America remains the envy of the world. Republicans can embrace this positive condition while still preferring stronger borders and a reformed immigration system that keeps the criminals out.

What happens next? The most likely outcome is a narrow congressional fix on the family separation issue, while the remaining immigration problems remain, sadly, unresolved. Meanwhile, the President will continue to make his case for tougher border enforcement, and the Democrats will go down the catch-and-release rabbit hole. Just as they didn't in 2016, Democrats aren't going to like where that takes them.