By JONATHAN M. KATZ (AP) PORT-AU-PRINCE, Haiti — Opposition groups are threatening to disrupt Haiti's upcoming legislative contests over allegations that election officials are stacking the deck in favor of President Rene Preval's party in a bid to boost executive power.

Frustrations center on decisions by the nine-member, presidentially appointed provisional electoral council seen as giving an unfair advantage to Preval's newly created Unity party, which in just weeks has absorbed Cabinet ministers, the presidents of both parliamentary chambers and almost half the members of the lower house.

Opponents are especially upset over the disqualification of about 15 rival political groups ahead of the Feb. 28 elections, including ousted former President Jean-Bertrand Aristide's Fanmi Lavalas. Some allege Preval is attempting to load parliament with allies to push through constitutional changes or even seek another term.

"The game is rigged," former presidential candidate Evans Paul, a leader of the newly created Alternative coalition, told The Associated Press. "The only way to confront Preval's plan is to mobilize the population."

The electoral council has not fully explained the disqualifications or addressed other allegations. A council spokesman declined requests to comment.

Paul, who helped lead opposition to Aristide ahead of his 2004 ouster, called for the electoral council to be replaced and some disqualified parties readmitted to the election. Otherwise, he said, opposition leaders will push for demonstrations.

"The people have a right to rebel whenever the government is acting anti-democratically," he said.

Lavalas supporters have also decried the electoral council's decision. Aristide broke a months-long public silence to criticize his party's exclusion in a radio interview, calling the decision an "electoral coup d'etat."

Some supporters have called for a boycott. Lavalas also boycotted Senate elections from which they were excluded earlier this year. Turnout was extremely low.

Unity replaces Preval's previous Lespwa movement, a loose organization created to win him the presidency in 2006. Recently converted Unity legislator Guy Gerard Georges, whose previous Union party was also disqualified by the council, said the new party paid members' $1,200 election inscription fee and would likely help finance their campaigns.

Most Lespwa members, including Preval, were either former Lavalas activists or had served under Aristide. But over the course of Preval's second, nonconsecutive term, the soft-spoken leader has drifted far from supporters of Aristide who helped push him to victory, and now he has cut ties with his own movement as well.

Lespwa members who did not follow Preval to the new party have also been disqualified by the electoral council.

If Unity secures majorities in the February election, its members are widely expected to push through constitutional amendments to expand executive powers. The current 1987 constitution severely limited government and executive powers in the aftermath of the decades-long Duvalier dictatorships.

"We will have the right and the ability to change the political direction of Haiti," Unity legislator Georges said, calling the current constitution outdated.

Some, including Paul, allege the president could be seeking changes so he could run for a third term in elections next year. The president has said he will not run again.

Any upheaval could wreck efforts led by Bill Clinton, who was named U.N. special envoy to Haiti this year, to increase private investment, especially in clothing exports, and boost tourism in the deeply impoverished country.