The G-20 economic summit in London officially gets under way today, but its most important message has already been issued.

Alas, not by President Obama.

The confab — which hosts the world’s 19 largest economies, plus the EU — is supposed to whip up a magic solution to restore the global economy. It’s a follow-on, actually, to last November’s G-20 gathering, convened in the heat of the global financial meltdown.

At that time, then-President George W. Bush used the occasion to tout the merits of free-market capitalism.

Recognizing that international responses to the financial crisis could quickly devolve into an assault on economic freedom, Bush wanted to make absolutely clear where the United States stood.

“If you seek economic growth, if you seek opportunity, if you seek social justice and human dignity — the free-market system is the way to go,” Bush said.

That was true six months ago — and it’s just as true today.

Yet, now we have a new president.

And while the G-20 offered an ideal chance for Obama to make his own unequivocal plea for free markets, he blew the opportunity.

Indeed, leading up to today’s event, the biggest defender of independent, free economies was Germany’s Angela Merkel — who put the kibosh on the massive global spending spree championed by Obama and the UK’s Gordon Brown.

“I will not let anyone tell me we must spend more money,” Merkel insisted.

Good for her.

Bitter memories of Weimar-era inflation are no doubt foremost in her mind; that’s what led to Hitler and the Nazis. Yet it’s a sad day indeed when the United States passes the pro-capitalist baton to anyone, let alone Germany.

Then again, it would have been hard for Obama to defend free markets with a straight face. Before heading to Europe, he’d announced that the government was moving to control yet further the affairs of two struggling auto companies, even firing GM head Rick Wagoner.

That’s not exactly how free markets are supposed to work.

All this, of course, is unlikely to have much impact on today’s proceedings. After all, the “agreement” the G-20 leaders will supposedly reach was hammered out by finance ministers days before the leaders even shook hands in London.

But it does say a lot about the future.

If Obama is willing to let Europe make the case for free-market capitalism, it may be time to say auf Wiedersehen to America’s global economic supremacy.