Francois Fillon saw off his last remaining rival on Sunday to be selected as the centre-right's candidate for the French presidency.
Francois Fillon, a 62-year-old from Le Mans, beat Alain Juppe by winning 67% of the vote compared to his rival's 33% in Sunday's run-off.
He had garnered around 44% of the vote in the first round of the primary last week in which five other candidates, including former president Nicolas Sarkozy, were eliminated.
In the eyes of many pundits, Fillon is now the frontrunner in the presidential race which will be decided next May.
President Francois Hollande, a Socialist, has been struggling in opinion polls after a term blighted by terror attacks in Paris and Nice that claimed hundreds of lives.
Current opinion polls suggest that far-right leader of the National Front Marine Le Pen would win the first-round of voting in the presidential election in April but would lose a run-off to her opponent in May.
Unless the Socialist Party can recover momentum, that would mean Fillon would be her likely opponent in the second round in which he would hope to assemble a coalition of voters as well as his base in the party now known as Les Republicains to keep Le Pen out of power.
Fillon, a father of five children from his marriage with his Welsh wife Penny, served as prime minister under Sarkozy as did Juppe, now 71, when Jacques Chirac was president.
Socialist Hollande's victory against the incumbent Sarkozy in 2012 ended 17 years of power for the centre-right but the terror attacks have seen a surge in support for Le Pen's National Front which has campaigned on a platform of security and against immigration.
Fillon campaigned on promises of slashing public spending, capping immigration, support for traditional family values and friendlier ties with Russian president Vladimir Putin.
In a sober victory speech, Fillon promised to defend "French values" and said France needs "a complete change of software".
Fillon goes forward as his party's candidate for next year's first-round of presidential polling on April 23 when the field of candidates across the political spectrum will be whittled down to two for the decider on May 7.