The Pakistan People's Party of slain former premier Benazir Bhutto is the most popular, with the country's two main opposition parties capable of a landslide victory in the key polls on February 18, a report based on recent surveys said on Monday.

A week before Pakistanis vote in the parliamentary elections, the "vast majority" -- 75 percent -- want President Pervez Musharraf to leave office, with his approval rating touching a new low of 15 per cent, the Washington Post reported.

Musharraf and his allies, the former ruling Pakistan Muslim League-Q, lose out in the surveys by separate US-based groups.

The PPP and the former premier Nawaz Sharif's PML-N, the two main opposition parties, had the backing of a combined 72 per cent of those surveyed by the conservative International Republican Institute between January 19-29.

In effect, if the two anti-Musharraf parties agreed, such support could give the PPP and PML-N a powerful coalition against the former general.

Fifty per cent of Pakistanis said they would vote for the PPP, against 22 per cent for the party of Sharif in the poll by the Washington-based institute.

Bhutto's PPP is "benefiting from both a wave of sympathy as well as a backlash against the government" following her murder late last year, the IRI said in its survey.

Pro-Musharraf PML-Q was chosen by only 14 per cent, said the survey reported by The Post.

Sixty-two per cent of Pakistanis blamed the government for the PPP leader's death at an election rally in Rawalpindi in December last year.

"This indicates a collapse in the government's credibility among its citizens," the IRI survey said.