The most interesting contest in Sunday’s first round of the French parliamentary election may well be the most irrelevant to determining whether President François Hollande’s center-left or the center-right will control the Assemblée nationale — but it also showcases that the far-left and far-right are both playing the strongest role in over a decade in any French legislative election.

The race is the 11th precinct of the Hénin-Beaumont region, where Front national leader Marine Le Pen is running against Front de gauche leader Jean-Luc Mélenchon.  Le Pen originally targeted the region in 2007 (where she won 24.5% of the vote) — it’s an economically stagnant area where coal mining was once the major economic activity.  Think of it as the part of Wallonia that’s actually part of France.*

Like many of the old French Parti communiste strongholds, it is today receptive to the economic populist message of the Front national — in the first round of the presidential election, Le Pen won 35% there, followed by Hollande with 27% and Nicolas Sarkozy with just 16%.

So it’s a constituency that Le Pen continues to view as fertile ground, a great pickup opportunity in what seems to be the Front national‘s best shot at seats in the Assemblée nationale since 1997.

Mélenchon, however, decided to parachute into the precinct to run against Le Pen (although neither have true roots in the region), prolonging the bitter antagonism that marked the presidential race.  In the spring, their enmity seemed greater than even that between Hollande and Sarkozy.

Mélenchon’s eagerness to attack the Front national led to a surge of support in the first round.  Although Mélenchon won less than some polls indicated he could have, his 11% total was still the best presidential result for the far left in two decades.

For a time, it looked as if Mélenchon’s move was a masterstroke — he would secure a seat for the Front de gauche and in so doing, polls showed, would become the left’s champion in defeating Le Pen.  As predicted, the campaign for Hénin-Beaumont has become a battle royale between the far left and the hard right, with rhetoric matching that of the presidential campaign:

“I find it funny the passion he has developed for me and that he follows me all across France,” Ms Le Pen remarked to a group of journalists at her constituency headquarters in the recession-hit town of Hénin-Beaumont. “But it is good. He divides people. There are people who would not vote for me if he wasn’t here.”

Speaking earlier as he greeted shoppers in a street market in neighbouring  Noyelles-Godault, Mr Mélenchon brushed aside the innuendo that he has some kind of obsession with his rival.

“I do not find her erotic, as I have read in certain newspapers,” he protested. He had become a candidate in Hénin-Beaumont to “shine a light on the vampires” of the National Front, he said. It would be “absolutely shaming” for the left if Ms Le Pen were elected in a former mining area “at the heart of the history of the French workers’ movement”.

And so on.

But as the campaign concludes, polls show an uptick for Parti socialiste candidate Philippe Kemel, who had previously polled far behind the two national stars — even the retiring PS deputy had abstained from endorsing Kemel.

Two polls on Wednesday showed a tight race, however:

• An IFOP poll conducted for the local paper La Voix du Nord showed Le Pen with 37%, Mélenchon with 25%, Kemel with 21.5% and 13% for Jean Urbaniak, the joint candidate of Sarkozy’s Union pour un mouvement populaire and the centrist Mouvement démocrate headed by François Bayrou. Mélenchon would win a runoff against Le Pen with 52%.
• Another OpinionWay poll for Le Figaro showed Le Pen with 32%, Kemel with 25%, Mélenchon with 24% and Urbaniak with 15%; Kemel would defeat Le Pen 53% to 47% in a runoff, while Mélenchon would defeat Le Pen 51% to 49%.

Both polls showed signs of Le Pen strengthening her first-round support, with Kemel rising at Mélenchon’s expense — perhaps a honeymoon effect for the PS candidate following Hollande’s election and the popular appointment of Jean-Marc Ayrault as prime minister, who campaigned for Kemel on Thursday.

That the Hénin-Beaumont race has become such a marquee contest underscores not only the national profiles of Le Pen and Mélenchon, but also that both the far left and far right will be much more robust in the 2012 elections.  In contrast, the 2002 and, especially, 2007 elections were relatively straightforward affairs between Sarkozy’s Union pour un mouvement populaire and the Parti soicaliste.

Under France’s two-round system, a candidate wins in the first round only if he or she wins over 50% of votes cast and at least 25% of all registered voters (regardless of whether such voters actually cast a ballot — think of this as “potential voters”).  If not, each candidate that wins at least 12.5% of all registered voters advances to the second round (or, alternatively, if no one reaches that level of support, the top two candidates advance).  This leads, in some instances, to triangulaires or even, rarely, quadrangulaires, i.e. runoffs in which three or four candidates emerging to the second round.

In 2002, there were 10 triangulaires and in 2007, only one triangulaire; in 1997, there were fully 79 triangulaires, 76 of which were runoffs among the two main parties and the Front national.  Sunday’s election should see strong enough support for the Front national and the Front de gauche that the second round could see perhaps over one hundred triangulaires.

Although the Front de gauche has not made a formal electoral pact with the Parti socialiste, it is presumed that in triangulaires with two leftist candidates, the candidate receiving the smaller amount of support will stand down in the second round in favor of the other candidate.  Those negotiations will depend on how well the far left does on Sunday — a strong result may even lead the Parti socialiste government to make policy concessions or government appointments to the far left.

Meanwhile, there’s absolutely no chance that Le Pen’s candidates will stand down for UMP candidates in the second round.  Le Pen’s strategy of aggressively attacking the UMP — currently, in a bit of chaos and without a clear leader — is designed to strengthen her bid to pull the Front national further to the center and make it the main party vehicle for the right in France.  The Front national has not held more than a single seat in the French legislature since the 1986 election, in which it won 35 seats.  Her strategy, however, will undoubtedly lead to many second-round results where right-leaning voters will be split, facilitating the election of additional leftist deputies.  That happened in many of the triangulaires in 1997, when the Front national won a historically high 15% of the first round vote, a result Le Pen seems likely to replicate on Sunday.

So in a sense, the showy Hénin-Beaumont race has been mutually beneficial for both the Front national and Front de gauche in that it has energized supporters of both Le Pen and Mélenchon throughout France, and increased the chances that both far-right and far-left deputies will enter the Assemblée nationale.

* Wallonia is the economically depressed, French-speaking region of Belgium.