(Reuters) – Former Prime Minister Manuel Valls, long tipped to win the left-wing ticket for France’s presidential election this spring, trailed his rivals after a debate on Sunday where his immigration policies came under fire.

In the televised debate, Valls faced six other contenders ahead of a Socialist primary starting on Jan. 22 to pick a candidate who can keep next May’s presidential poll from becoming a contest between the centre-right’s Francois Fillon and Marine Le Pen of the far-right.

The candidate chosen in the primary’s runoff on January 29 could also have a crucial impact on the chances of independent Emmanuel Macron, a popular former economy minister whose campaign is rapidly gaining momentum, according to surveys.

An Elabe poll of 1,053 people of mixed political views published soon after Sunday night’s debate said 29 percent found former economy minister Arnaud Montebourg “more convincing” than Valls, who was put on 26 percent.

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