It’s a tradition in American politics, almost a law, that politics stops “at the water’s edge.” That means that our politicians don’t speak ill of their fellow Americans while visiting foreign countries, or dealing with foreign leaders. The reason for this tradition is fairly obvious: We don’t want to forefront our weaknesses and divisions when we’re dealing with other powers, but rather to act as a unit from a clear position of strength. Nor do we want foreign entities reaching into our domestic politics to use one faction or another as their cat’s paw to promote their own interests instead of ours.

On March 10, President Obama tossed that tradition out the window when he used a press conference welcoming Canadian Prime Minister Justin Trudeau to snark about the “crack-up” in the Republican party, and deflect any blame that might accrue to him for the rise of a figure who frightens many non-Americans, Donald Trump.

And in one sense, Obama is right. In his seven years in office, Obama has pushed relentlessly for a raft of far-left policies, on every issue from health care and immigration to same-sex “marriage” and gun control.

Unlike Bill Clinton, who governed from the left but reached out to the center, Obama has been unashamed in his attempts to fundamentally transform America legally, demographically and even constitutionally — as we saw in his radical activist Supreme Court nominations, and his abuse of executive orders to enact de facto amnesties for immigrants and confiscate Americans’ guns. His solicitor general, before the same-sex marriage case was decided, admitted before the Supreme Court that the IRS might treat faithful Christian churches which refused to approve such unions as it treated segregationists — that is, strip their tax exemptions.

No one could plausibly accuse Barack Obama of tacking toward the center, in order to split Republicans and create a governing coalition. His relentless promotion of “progressive” programs at home, and his overt attempts to reduce and dissipate U.S. influence abroad, should have been enough to spark a fierce and ongoing Republican resistance, by members of Congress who were elected or re-elected on the promise that they would do just that — fight back against Obama with every weapon that came to hand.

That promise was the fodder of Obama’s attack on Republicans at the press conference. He accused GOP leaders of “feeding the Republican base for the last seven years a notion that everything I do is to be opposed” and “that cooperation or compromise somehow is a betrayal, that maximalist, absolutist positions on issues are politically advantageous.”

But of course the Republican leadership never kept such promises, or took such campaign rhetoric seriously. Again and again, Republican leaders talked tough in the beginning, then faced with the threat of a government shutdown, got spooked and gave in to Obama — surrendering the “power of the purse” which our nation’s Founders had put in their hands precisely to restrain radical executives like Obama. On same-sex marriage, several mainstream Republican presidential candidates mumbled kind words about religious liberty, then started talking about “settled law” and changed the subject.

A recent surrender was Speaker Paul Ryan’s support of the “omnibus budget” that fully funded many of Obama’s radical actions, from his executive amnesty to his new embassy in Cuba. Republicans who urged their fellow legislators to fight as they had promised, like Senator Ted Cruz, found themselves frozen out and isolated by their own party’s leadership.

Instead of Republicans unifying to fight the relentless advance of President Obama’s radicalism, they split into factions — a leadership faction willing to collaborate with Obama rather than face the political firestorm they feared from a government shutdown, and increasingly restive conservatives who kept hearing from their inflamed and frustrated voters. Then the presidential primaries exposed and deepened the divides within the party.

The issue on which the party’s donor base and organizational leadership was furthest divided from its electoral base was immigration. According to a recent report by the Center for Immigration Studies, nearly one in five Americans is either an immigrant or the child of recent immigrants. It is hard to call “conservative” or even “moderate” a set of policies that goads a constant influx of people who mostly have little or no allegiance to America’s experiment in ordered liberty, limited government and self-reliance, while fueling demands for ever-larger government programs to manage the social problems that so many low-skill immigrants bring with them, and stricter enforcement of “diversity” policies in government, education and business to suppress popular resentment at those changes.

Nevertheless, the GOP candidates who ran with strong financial backing from its “establishment” network of high-dollar donors, Jeb Bush and Marco Rubio most prominent among them, doubled down on their long-standing proposals to offer legal status, even citizenship, to illegal immigrants, and vastly increase legal immigration, both among high and low skill newcomers. The two candidates who strongly opposed such policies, Donald Trump and Ted Cruz, were both treated as essentially illegitimate candidates by a party machinery that simply cannot imagine following the wishes of its own voters on such a crucial issue.

Tens of millions of wasted campaign dollars later, Bush is out of the race, Rubio is fighting off calls from his own supporters to drop out, and the party is likely faced with a stunning choice: between Ted Cruz, a stern Congressional rebel against the GOP leadership, and Donald Trump, an angry, sometimes thuggish populist whose incoherent and shifting views matter less than the cult of personality he has unleashed.

Obama was wrong to attack Republicans in front of the Canadian prime minister — bad form, as the English would say. But he can hardly be faulted for GOP disunity. His far-left agenda should have united a healthy conservative party as it joined together to push back, as the Democratic House during Republican President Ronald Reagan’s two terms fought tooth and nail against his policies. But instead of uniting, the GOP shattered along its fault lines.

It remains to be seen in the next few days and weeks if the party’s elites are willing to make reasonable concessions to its voters and unite at last around the figure of Senator Cruz, or whether those leaders are willing to see Donald Trump gain the nomination and lead the party to likely defeat in November. Maybe they’re hoping that such a disaster will finally beat the base down into submission, or perhaps purge it of its “inflexible” conservatives. I’m reminded of the old crack about a government that was dissatisfied with its people, so it chose to elect a new one.