Stephen Miller, President Trump's irritable White House aide, declared on national TV over the weekend that the president was "absolutely" ready to make good on his threat to shut down the government if he doesn't get money for his border wall in the upcoming appropriations bill. "This is a very fundamental issue," yelled Miller at George Stephanopoulos. "At stake is the question of whether or not the United States remains a sovereign country."

Tough border controls do not make a sovereign country more sovereign. A county that opens the door to immigrants is exercising its sovereignty just as much as one that doesn't. If that were not the case, North Korea would be the only sovereign nation on the planet.

That said, everyone should be rooting for Trump to follow through on his threat to shut down the government. This is especially true of opponents of the Great Wall of Trump. The president simply won't back off from his insistence on the wall so long as there's any ambiguity around whether it will cost him politically. And there are good reasons to believe it will.

Trump has been threatening a government shutdown over the wall almost from the get-go. This time he is demanding $5 billion — down from the $25 billion he asked in January. But even in May of last year, he tweeted the country "needs a good 'shutdown'" in September to "fix [the] mess" at the border. RealClearPolitics' Bill Scher has pointed out Trump has kept this threat alive throughout 2018 — issuing it virtually every month in April, June, July, and early September, only to flinch when congressional Republicans, terrified that a shutdown would torpedo their midterm prospects, prevailed on him to back-off and make a deal to keep the government funded.

Perhaps because of this retreat, the midterm elections didn't deliver a shellacking big enough to make the political downside of such a hardline strategy clear to Trump. The GOP lost 40 seats in the House, but it also gained two in the Senate. That was enough for Trump to declare the results a "tremendous victory."

But a post-election analysis by David Winston, a leading GOP pollster, found that voters who waited until the last few days to make their decision went Democratic by a 12-point margin. What's more, voters broadly were 59 percent less likely to back Republicans after hearing their message on immigration and 63 percent less likely after listening to them talk about border security and the migrant caravan. On the other hand, they were 76 percent more likely to vote GOP after hearing about jobs and the economy.

This means Trump's decision to tout immigration over his real economic accomplishments was a blunder of epic proportions. But his push for the government shutdown suggests he's not persuaded, even though the latest Marist/NPR poll shows 57 percent respondents overall would like Trump to compromise. Trump is mainly interested in playing up to his base. That makes a certain amount of sense given that he wouldn't be sitting in the White House without its support. And with his Republican base, the government shutdown over the wall is wildly popular, with 65 percent of Republicans telling him to go for it. Only 29 percent Republicans favor a compromise. Among Democrats, by contrast, 71 percent believe Trump should back off.

But Gallup polls show self-identifying Republicans are only 28 percent of total voters and Democrats 31 percent. Meanwhile, 39 percent of voters regard themselves as independent.

So assuming Trump has more or less bottomed out among Democrats, the question is whether a shutdown will result in more gains among Republicans than losses among independents — and vice-versa if he compromises.

Let's see: Among all eligible voters, there are 40 percent more independents than Republicans. And 61 percent of independents oppose the wall even without a government shutdown while 36 percent support it. With the government shutdown in play, the number of independents opposed is likely to soar. So the losses among independents are likely to be far greater than gains from Republicans.

Trump, however, doesn't believe this because, as far as he is concerned, border security and immigration controls have untapped voter appeal. That's why, he thinks, Democrats were forced to back off when they shut down the government to push the legalization of DREAMers earlier this year. So it wasn't the government shutdown that was unpopular, as far as Trump is concerned, but the Democrats' cause.

His reasoning is, of course, nonsensical. Legalizing DREAMers was far more popular than the border wall ever was with voters. Of course he won't believe this — unless he gets an overdue shellacking. Only if his poll numbers plummet below the persistent 40 percent approval rating he has enjoyed thus far will he be convinced that shutting down the government isn't worth it. At that point, he might moderate his constant attacks on immigrants for the simple reason that after a point, they backfire — they don't win him friends or voters.

So everyone should hope that sounder minds and cooler heads don't prevail and Trump tries to decisively overreach by shutting down the government. Only when he understands that he can't "keep winning" by playing to his base alone will he call off his constant attacks on immigrants.