WASHINGTON - Super Tuesday essentially sealed the deal. A more united party might have been able to defeat him a few weeks ago, but Donald Trump has gathered a sufficient lead in delegates and accumulated real support from a broad range of GOP voters over the past nine months to all but sew up the nomination to be the Republican Party's candidate. For November, it means that foreign leaders will likely get the president they expect, Hillary Clinton. Even if U.S. allies in Europe and beyond should not expect a Trump presidency, they should fear its possibility, and regardless of the November result, they should be concerned about the weakening internationalist center of U.S. politics.

The GOP establishment's last hope, Florida Senator Marco Rubio, won Minnesota Tuesday, but this was his only victory among the first 15 states. A comeback from such results would be unprecedented. Texas Senator Ted Cruz, a conservative hardliner not well-liked among many party elites, won his home state plus Oklahoma and Alaska Tuesday, but needed to do better across the South to be viable.

This leaves Trump with 285 of the delegates, which are awarded based on the results of primary and caucus votes and which actually choose the party nominee, to Cruz's 161 and Rubio's 87. He needs 1,237 to seal up the nomination, and leads in Florida and Ohio's upcoming primaries, which are winner-take-all. Clinton has 1,001 delegates in the Democratic race to Vermont Senator Bernie Sanders' 371, a lead she earned by winning over African-Americans by decisive margins and that is padded by a massive advantage among "superdelegates," party officials who are free to vote for whom they choose.

There are two major reasons to predict that Clinton would beat Trump in November.

One is the combination of demographics and the Electoral College system, which gives the Democratic Party a significant advantage in the presidential race (the GOP has a parallel advantage in Congress). In the race to a majority (270 of the 538 electoral votes), only seven states are likely to be competitive - Florida, Ohio, Virginia, Colorado, and Nevada, all of which supported Barack Obama twice and George W. Bush twice, as well as Iowa and New Hampshire. This means the Democrats essentially start at 247 votes and the Republicans at 206. Florida alone would give Clinton the White House. A Republican would need to more or less sweep the competitive states -possible if the stars align, but he would start at a disadvantage.

The second reason is the state of the Republican Party. A Democrat has won the popular vote in five of the past six presidential elections. Obama is still fairly popular, at least among Democrats. Even though GOP strategists suggested tacking toward the center in their postmortem of the 2012 loss to Obama, the Republican primary has seen the party taken in the opposite direction by most of its presidential hopefuls (Ohio Governor John Kasich is the notable exception) and taken over by an self-promoting businessman and reality TV star.

While a comeback by Rubio, Cruz, or Kasich or a contested convention may be a chimera, Republican leaders could still block Trump from winning the presidency. Many GOP politicians will line up behind the popular Trump. But freshman Nebraska Senator Ben Sasse and a cadre of former officials and conservative intellectuals (foreign policy intellectuals in particular) have proclaimed #NeverTrump, swearing to support Clinton or a third-party run by a "true conservative" instead.

While Clinton - an experienced, if flawed, leader of the Democratic establishment - would be a strong favorite against Trump, the result cannot be a foregone conclusion. Trump's unexpected success so far should teach us that much.

What does all of this mean for Europe?

The main lesson of the 2016 race is that trends in both political parties indicate the U.S. political center is weakening, which in turn indicates a gradual (or sharp) U.S. retreat from its decades-long role of "benign" liberal global hegemon. Clinton has had to fight off a stronger than expected challenge from the left in the person of Sanders, and came out against the Obama administration's Trans-Pacific Partnership. Trump has made "unfair" terms of trade a top campaign theme, while both Trump and Cruz have adopted a more isolationist foreign policy stance. Strategic partnership with the United States will continue to be an asset, but allies may want to consider the risk of strategic dependence on a United States trending toward retrenchment.

Secondarily, Europe knows from experience that nationalist populists can thrive when governments do not meet voters' expectations, and authoritarian personalities can capture and degrade liberal democracies in times of trouble. Eloquently delivered history lessons from European leaders might find a few ears among U.S. voters. At least one can hope.

(AP photo)