PARIS (AP) -- France's regional election runoffs Sunday has taken on extra importance after Marine Le Pen's far-right National Front party dominated first-round voting, selling its anti-immigrant, tough-on-security message to voters worried about an unprecedented wave of refugees and Islamic State violence.
Here's a look at what's at stake:
LE PEN'S PROSPECTS
The vote — the last nationwide election before France's 2017 presidential vote — is seen as a gauge of political sentiment, especially Marine Le Pen's presidential chances.
While National Front party lists dominated in six of France's 13 regions, several polls suggest it could lose that edge in Sunday's final round.
Le Pen herself is facing a tough challenge by conservative former labor minister Xavier Bertrand in the northern region of Nord-Pas de Calais-Picardie. Likewise for her niece, Marion Marechal-Le Pen, running in the southern region of Provence-Alpes-Cote d'Azur against conservative Nice Mayor Claude Estrosi.
The two National Front women scored more than 40 percent each in the first round. That's in part because the struggling Socialists, the party of President Francois Hollande, withdrew their candidates in both regions in favor of rival conservatives — in hopes of keeping the Le Pens out of power.
But the outcome Sunday remains unclear. The nearly 50 percent of people who failed to cast ballots in the Dec. 6 first round could hold the key to the runoff.
MIGRANTS AND MUSLIMS
Le Pen has worked hard to soften the image of her party from the days it was run by her father, Jean-Marie, repeatedly convicted of racism and anti-Semitism.
The party's main target is immigrants, and what Le Pen sees as a threat to France from Islam. Le Pen and her niece have said that they would refuse funding to interests representing a single community, a reference to Muslim groups.
The National Front's long-standing calls to increase security and lock out immigrants dovetailed this year with two deadly attacks by Islamic extremists in Paris and an unusually large influx of migrants to Europe.
Another nemesis of the National Front is the European Union. The party wants to pull France out of the 28-nation EU and the shared euro currency and restore what it touts as the country's past greatness.
That resonates with many voters frustrated that governments left and right have failed to bring down France's 10 percent unemployment and at France's shrinking global economic clout.
Far-right and nationalist parties have gained ground across Europe in recent years, from Greece to Hungary, Austria, the Netherlands and elsewhere — partly due to Europe's immigration crisis.
RISING RIGHT, LIMPING LEFT
All but one of France's regions are currently run by the Socialists, who have seen their support shrivel since Hollande won the presidency in 2012.
The Socialists came in an embarrassing third place in the nationwide vote in the first round, though polls suggest they could win back a bit of support in the runoff.
Former President Nicolas Sarkozy's conservative Republicans party may come out on top Sunday, taking several regions. Sarkozy, also eyeing a 2017 presidential bid, would welcome such a victory.
Prime Minister Manuel Valls has led the Socialist charge against the National Front — and warned Friday that its victory could sow divisions that "could lead to civil war."