Apathy main election rival for Algeria's Bouteflika

* President Bouteflika on course to win third term

* Analysts predict disillusioned voters could stay at home

* Bouteflika touts stability and promises investment

By Christian Lowe and Lamine Chikhi

ALGIERS, April 9 (Reuters) - Algerians vote on Thursday in an election that President Abdelaziz Bouteflika needs to win convincingly to show he can re-connect with disillusioned voters and snuff out a lingering Islamist insurgency.

Bouteflika, a 72-year-old veteran of Algeria's war for independence from France, is expected to win by a big margin but if voters stay away from the polls that could boost opponents -- including Islamists -- who say the vote is a charade.

"Voting or not will make no difference as Bouteflika will win anyway," political analyst Nacer Djabi told Reuters. "This is why a poor turnout is likely."

In Algeria's capital, a teeming city of white-washed French colonial buildings perched above the Mediterranean Sea, buses and lampposts are covered in posters urging voters to back Bouteflika. Rival candidates' posters are invisible.