President Trump lately draws the ire of establishment politicians on both sides of the aisle by threatening a showdown over the border: either build the wall -- or shut the government down when we face yet another budget deadline just weeks before the November midterm elections.

I encourage President Trump to engage in this battle and, if necessary, as they say in mob movies, “go to the mattresses.” Why, and why now?

First, because the border remains the foundational animating promise of the entire 2016 movement. That movement, in fact, was a global groundswell that preceded Trump and demanded the resurrection of national sovereignty, from Great Britain to Italy to the Rio Grande Valley of south Texas. Despite the nattering howls of globalists and mainstream media elites, real borders do not represent xenophobic, backward-looking constructs, but rather the very bedrock basis of any healthy nation-state.

Trump masterfully tapped into the angst created by our decades-long appeasement at the border. Congress’s tacit consent of nearly open borders benefited the wealthy who prefer cheap labor and politicians seeking new constituents, some of whom now legally vote in places like San Francisco – without obtaining citizenship. But Trump saw the harm of uncontrolled illegal immigration, problems ranging from the depressing of working-class wages to thousands of citizens victimized by criminals who should never have been in our country in the first place.

Why pick this fight now? Conventional wisdom and political prudence would dictate waiting until after the midterms and hoping for a more Trumpian Congress. Senate Majority Leader Mitch McConnell, for example, said that funding the wall would “probably” have to wait. But such thinking belies the reality that we Republicans face in coming months. Historically, the first midterm for a new president proves disastrous for his party; just ask Barack Obama or Bill Clinton, both of whom lost control of the House in their first such plebiscites.

In addition, the GOP faces a record number of retirements, many of them very veteran members of the House, putting almost all the onus to defend seats on Republicans. Finally, recent polling remains foreboding, with a GOP deficit in the generic ballot widening to a whopping seven percentage points in the RealClearPolitics polling average.

So, the present is no time for temerity or coasting into November. Instead, the best way to score an upset win at the polls is for Trump to effectively put himself on the ballot. One powerful way to accomplish that goal is by highlighting immigration, his signature issue that has surged to the top of polls ranking matters of voter concern.

Given the recent leftist lunacy from major Democrats denouncing federal law enforcement and demonizing ICE, this issue plays terrifically for the GOP and can galvanize Trump voters who handed him victory in 230 of the House’s districts in 2016, vs. 205 for Hillary Clinton. Moreover, few Americans outside of open-borders radicals, media elites, and big business executives support lax immigration controls. According to a recent Economist/YouGov poll, 64 percent of Hispanics prefer detention of illegal border crossers, either alongside children or separately, until their trial, and only 20 percent support the prior “catch and release” practice. In addition, Trump’s overall approval rating among Hispanics has soared lately. If the Congress can combine a sensible DACA compromise with a fully barricaded border, then GOP electoral prospects for 2018 and beyond vault higher.

So, both policy and politics point to the efficacy of a showdown over immigration. Even if the measure ultimately fails in the Senate, the vote will crystalize the issue before voters, rally the Trump coalition of deplorables, and likely prevent a Democratic takeover of the House that would surely lead to impeachment proceedings.

Mr. President, it’s time to go to the mattresses. Build the wall, or shut Washington down.