The question of the moment is whether this White House border plan plays out differently than those that fizzled before.
Nearly one year ago President Donald Trump signed an executive order rescinding his own famous "zero tolerance" policy.
Under the policy children had been removed from families, prompting condemnation across the political spectrum. Critics included four former first ladies , Pope Francis, and even Melania Trump.
Six months later, Trump retreated again from another of his border security plans. He had forced a record-long government shutdown over border-wall funding, but caved with Congress giving him nothing to show for it.
The border problem Trump calls a menacing invasion continues to grow. On Wednesday, officials said that Central American migrants came to the U.S.-Mexico border in May in the highest monthly numbers in seven years.
Customs and Border Protection took more than 144,278 migrants into custody last month, up by one-third from April.
Now Trump vows to impose tariffs on all imports from Mexico in his latest bid to stop migrants.
The Republican caucus in the Senate has never quite backed Trump's other border strategies. Family separations were canceled a day after Majority Leader Mitch McConnell (R-Ky.) said his members wanted "a plan to keep families together while their immigration status is determined."
While the shutdown dragged on, McConnell was willing to let the newly Democratic-run House of Representatives take verbal heat from Trump. But in the end both houses approved a bill with no wall concessions.
And when the president invoked emergency powers to fund the barrier without Congressional approval, the GOP Senate went on record against it, boosting court efforts to stop it.
Last time out, Trump assailed the Democrats as champions of open borders. On tariffs, however, resistance now arises from within his own party which tends to favor "free trade.”
Sen. Ted Cruz (R-Texas) reportedly called Trump's tariff plan a $30 billion tax increase on his constituents. Sen. John Cornyn (R-Texas) said: "We're holding a gun to our own heads."
Rather than belittle his party as weak on immigration, Trump this week just said GOP lawmakers would be "foolish" to legislate against the 5 percent tariff due to commence Monday.
If a standoff follows, however, he could face his first veto override as president on the eve of national elections next year.
The ideal scenario for Trump would be that the Mexican government drastically curbs the flow of migrants to the U.S. border as he demands.
The prospects for that result sound uncertain at best.
“To avoid these flows that go from Central America to the United States in large numbers I think we can make progress with traditional mechanisms and better exercise existing rules,” said Jesus Seade, Mexico’s deputy foreign minister for North America.
Since the biggest resistance to the Mexico tariff threat comes from his rival senators across the aisle, Minority Leader Chuck Schumer (D-N.Y.) said this week: "Frankly, I don’t believe that President Trump will actually go through with the tariffs.”
"President Trump has a habit of talking tough and then retreating, because his policies often can’t be implemented or don’t make sense … so I wouldn’t be surprised at all if President Trump doesn’t follow through on these tariffs either."
Predictably, Trump responded to the dare by calling Schumer names and denying any bluff.