PARIS (Reuters) -- France's defeated presidential candidate Segolene Royal will not stand for re-election in next month's parliamentary ballot, a senior aide said on Friday.

The decision could complicate her efforts to stamp her authority on the Socialist party, which faces internal strife following its third consecutive loss in a presidential election.

Royal is president of France's western Poitou-Charentes region and she made a point during the election campaign of saying politicians should only hold one elected office.

Her presidential campaign director Jean-Louis Bianco said she had decided to stick to her principles and would renounce standing for re-election in her Deux-Sevres constituency, which she has represented since 1988.

The Socialist party is widely expected to lose the parliamentary election, with opinion polls saying voters will hand president-elect Nicolas Sarkozy a strong majority.

Parliament is the natural platform for the leader of the opposition and Royal's absence will diminish her profile, but not necessarily her ambition to play a major role in the party.

"She will have no problem to exist politically," Bianco told Reuters.

Royal tried to shunt France's hidebound Socialist party towards the center of the political spectrum during her election campaign in a desperate effort to overtake Sarkozy.

Despite her defeat, many analysts believe the party must continue in this direction if it wants to regain power.

Royal made clear on the night of her defeat that she wanted to play a central role in the Socialist party, surprising some veterans who had expected her to retreat into the shadows. "You can count on me to deepen the renovation of the left," Royal said on Sunday. "I will be present for this essential work and I will assume the responsibility which now falls upon me."

Newspaper commentators said her statement amounted to a takeover bid for the party, which is currently headed by Francois Hollande, the father of her four children.

An opinion poll on Friday said 40 percent of people thought she should lead the party campaign for the legislative vote.

The next highest score was 28 percent for former finance minister Dominique Strauss Kahn, seen as the most moderate of the Socialist heavyweights.

He has already made clear his ambition to take over the party, attacking the strategic vision of Hollande, who took over as party chief following its 2002 presidential rout.

"The French have understood that (the party) has distanced itself from reality. They want a left that is real, efficient and concrete, not tied by an ideology that doles out yesterday's solutions," he said in a speech on Thursday.