Jean-François Copé has won a leadership vote to head France's opposition centre-right UMP party, an internal party commission has confirmed, reports the BBC.
Mr Copé and rival François Fillon have traded accusations of fraud since the 18 November election, which an initial count said Mr Cope had narrowly won.
After a fresh ballot count, the commission found that Mr Copé had won by almost 1,000 votes.
However, Mr Fillon rejected the commission's decision as "illegal".
He had contested the vote, saying many votes from France's overseas territories have not been counted.
After the new count, which discounted contested areas and added overseas votes, Mr Cope said: "The committee has confirmed my election. It has even recorded a bigger margin in my favour. The result is there. Everybody must now respect it."
But Mr Fillon, a former prime minister, said in a statement quoted by AFP news agency: "Once again, Jean-Francois Copé has announced that he is president [of the party] by force."
Mr Fillon added that he did not consider the committee impartial.
Read more of this report from the BBC.