More than 12,000 people are eligible to cast votes Tuesday for a new state legislature representative in the rural Manek Urai of northern Kelantan state, which has been ruled by the opposition Pan-Malaysian Islamic Party, or PAS, since 1990.

Prime Minister Najib Razak has pledged numerous political and economic reforms since taking office in April, but analysts said the PAS appears certain to fend off efforts by his United Malays National Organization to take the seat. It became vacant after the Islamic party's incumbent died of heart failure in May.

"It's a no-brainer. PAS will win for sure. It's a hardcore PAS area," said James Chin, a political science professor at Monash University. But PAS might win with a reduced majority compared to general elections last year because UMNO has campaigned heavily over the past week, he said.

"These are the kinds of seats UMNO needs to prove that it can win, in terms of meeting Malays' interests," said Ibrahim Suffian, director of independent research firm Merdeka Center.

A nationwide poll in late June by the center showed that Najib's approval rating had risen from 45 percent in mid-May to 65 percent, likely because many people are warming to his plans for changes such as rolling back an affirmative action program for Malays.

The telephone survey of about 1,000 people had a margin of error of 3 percentage points.

Najib succeeded an unpopular prime minister, Abdullah Ahmad Badawi, who presided over the ruling National Front coalition's worst-ever election results last year. The coalition, led by UMNO, has been accused of allowing corruption and racial discrimination to become rampant.

The Manek Urai special election will be the seventh since the March 2008 general elections, in which an opposition alliance that includes PAS and two other parties won more than one-third of the seats in Parliament.

The opposition has won five of the by-elections so far, but key alliance officials have squabbled in recent weeks over policy decisions.