Paris - The losing Socialist Party candidate in the 2007 French presidential election, Segolene Royal, will be standing later Friday in a run-off election to become party leader.

If she beats her opponent, Lille Mayor Martine Aubry, she will take a large step to securing her party's nomination to face President Nicolas Sarkozy in the 2012 presidential election.

In 2007, Royal became the first French woman to make it to the second round of the presidential election, but she was soundly beaten by Sarkozy.

In Thursday's first round of balloting for the party leadership, the 55-year-old Royal garnered 43.1 per cent of the vote, compared to Aubry's 35.4 per cent and 22.8 per cent for European Parliament deputy Benoit Hamon.

Hamon urged his supporters to vote for Aubry, making her the putative favourite in the run-off.

But Hamon's support came primarily from young Socialists, many of whom will probably be drawn to Royal's call to reduce the cost of party membership and to hold US-style primaries to select Socialist candidates for national office.

Royal has also urged an electoral alliance with the centrist Modem party to defeat Sarkozy, an option the 58-year-old Aubry has rejected for the time being.

However, in her successful campaign for the Lille City Hall, she forged a deal with the centrists to beat her conservative opponent.

Whoever wins, the Socialist Party - which is widely considered old-fashioned and slow to change - will have its first-ever female leader.

Some 233,000 dues-paying members are eligible to vote on Friday. Polls close at 2100 GMT, with results not available until midnight. (dpa)