Just three months ago, the video shown above from yet another EU summit set tongues wagging on both sides of the English Channel: was French President Nicolas Sarkozy so angry with UK Prime Minister David Cameron that he’d brush past his outstretched hand?

Cameron had just exercised the United Kingdom’s first-ever veto of a European Union fiscal treaty that would have brought the EU countries into greater fiscal policy alignment (presumably toward more austerity, as favored by Cameron, Sarkozy and German chancellor Angela Merkel).  Although the remaining 26 EU countries signed up to a “compact” of the EU countries (sans the UK), the exercise of the veto was very much in keeping with the UK’s longtime role as Europe’s most stubborn citizen, much to the anguish of Sarkozy and the rest of Europe.

So it may be surprising to see that Cameron did not meet with frontrunning Parti socialiste presidential candidate François Hollande during his trip to London this week, and even more surprising to read Cameron’s very pro-Sarkozy statements to Le Figaro last week, in which Cameron made clear that he is strongly supporting Sarkozy’s reelection bid, with an endorsement that’s very nearly as strong as the endorsement Merkel provided earlier in February:

Nicolas Sarkozy est un dirigeant du centre droit et je lui souhaite bonne chance. Il a de grandes qualités de chef, c’est un homme politique courageux. Il a fait des choses extraordinairement importantes pour la France. Ce sera au peuple français de décider, je n’ai pas à interférer dans son choix. Nicolas Sarkozy a mon soutien. Je le dis clairement. Mais je ne suis pas sûr que si je sillonnais la France en bus pour le soutenir, cela serait efficace.

In translation: “Nicolas Sarkozy is a leader of the center-right and I wish him luck. He has great leadership qualities, he’s a brave politician. He does extraordinarily important things for France. This will be the French people to decide, I do not have to interfere in his choice. Nicolas Sarkozy has my support. I say it clearly. But I’m not sure if I criss-cross France by bus to support it, it would be effective.”

Cameron can point to traditional prudence, of course, in refusing to meet with candidate Hollande. Cameron can also point out that he and Hollande lie on opposite poles of the ideological spectrum.  Hollande is pushing for increased spending in France and in Europe to spur growth.  Cameron, quite the contrary, has pushed through painful austerity measures in the UK to reduce British debt, even as growth stalls in the UK.

Although Sarkozy and Cameron have recently joined together to support the military efforts to oust Libyan dictator Muammar Gaddafi , that they have had a rocky relationship since Cameron came to Downing Street in May 2010.

For a more traditionally intergovermental, “Euroskeptic” actor like the UK, it may well make more sense to see Hollande off to the Élysée, where it is thought that his political disagreement with Merkel could weaken the Franco-German front for ever closer European integration (but may also jeopardize the financial market’s sense of security that Europe will muddle through its sovereign debt crisis).  While this result would be feared throughout most of Europe (and maybe the world), it is something that many in the UK, especially on the right, might welcome.  Britain’s Tories have never been enthusiastic about the EU project and indeed, Cameron’s strong support has caused some backlash in the UK.

While France is an original member of the EU’s predecessor (the post-war European Coal and Steel Community and then the European Economic Community), uses the euro as its currency and is seen as the engine of the EU alongside Germany, the UK has retained the pound and did not join the EU’s predecessor until 1973, and even then after then-French president Charles de Gaulle vetoed the UK’s membership.  In the 1980s, UK prime minister Margaret Thatcher renegotiated the UK’s membership for a “rebate” of the UK’s financial contribution to the EU and served as a foil to then-EEC president Jacques Delors (a former French financial minister) in his quest to establish the single currency.

So Cameron’s active support for Sarkozy will undoubtedly displease the significant portion of his party that remains opposed to further EU involvement over British economic policy.  Win or lose, support for Sarkozy could be seen as giving unforgivable succor to a stronger Europe.  But if, as polls show is likely, Hollande defeats Sarkozy, the endorsement will make it ever more difficult for Anglo-French relations, just as Merkel’s early endorsement may complicate Franco-German (and ultimately EU) relations.

While I’ve written that Sarkozy has to take a stridently populist tone to project a strong finish in the first round, emphasizing immigration, unemployment benefits and other reforms, his second-round success depends on showing that he is infintely better suited for this particular moment in the EU crisis.  Sarkozy will have to imply that a Hollande victory could lead to a panic among investors that the EU won’t be able to agree on key fiscal and monetary policy matters, perhaps pushing the sovereign debt financial crisis into a metdown scenario that Sarkozy, Merkel and other key EU players have taken pains to avoid since 2010, and that would probably envelop the United Kingdom as well, for better or worse.

In that light, the Merkel and now Cameron endorsements are absolutely key to that strategy — Sarkozy will be able to tell voters that European unity is so crucial right now that even EU rivals as disparate as Merkel and Cameron agree that Sarkozy should be reelected, notwithstanding French preference for Hollande.  (Keep in mind that the second round will likely follow what can only be described as tense parliamentary elections in Greece sometime in April).

It’s a risky strategy — for Merkel and Cameron above all. French voters all but sunk the EU constitution in 2005, so it’s not altogether clear that Europe is the strongest rallying card for Sarkozy.  But if it works to reelect Sarkozy, against all odds, it would mark a watershed moment, not only in French politics, but in European politics.