Indonesia's presidential election race remains wide open despite a decision by the powerful Golkar party of former dictator Suharto to back incumbent Megawati Sukarnoputri – a move unlikely to swing the vote, observers said.

In a decision announced Sunday, Golkar deputy chairman Slamet Effendy Yusuf said the machinery of the huge party, which won April 5 legislative polls, would work towards victory for Megawati in the September 20 presidential vote.

The move follows an intense period of horsetrading in the wake of a July 5 first round poll, which saw the president finish second behind her former security minister Susilo Bambang Yudhoyono.

Both candidates have been battling to woo the support of parties whose presidential hopefuls fell by the wayside in the initial round, with the endorsement of Golkar seen as top prize.

With only 27 percent of the vote in the July polls, behind Yudhoyono's 33 percent, Megawati has the strongest need for Golkar's support – potentially worth the 22 percent scored by its candidate, former General Wiranto.

Golkar's backing brings Megawati another 128 seats in the country's parliament to reinforce her Indonesian Democratic Party for Struggle's 109.

With the added support of the United Development Party, led by Megawati's current vice president Hamzah Haz, and that of the small Prosperous Peace Party, Megawati's coalition will account for 308 of the parliament's 550 seats.

But, say analysts, Megawati's coup has by no means won her the election, as an increasingly independent-minded and cynical electorate views the new alliance with suspicion. Worse still, the move could backfire on the president, who they say has offered too many concessions – notably the promise of eight cabinet seats – to Golkar and its leader Akbar Tanjung.

Political analyst Andi Mallarangeng of the Freedom Institute think tank said the president needed to focus on her grass roots supporters instead of wasting time on alliances that would only come into their own after the elections.

"Voters are now more independent in voicing out their aspirations. They will sneer at this type of coalition and regard it as nothing more than a horsetrading scheme," he told AFP. "Actually, the more effective strategy for Megawati is to win the hearts of the grass roots, because there is no guarantee that Akbar Tanjung can influence the minds of Golkar supporters."

Fellow Freedom Institute analyst Syaiful Mujani said Golkar's support for Megawati was "inevitable", but was merely a ruse by Akbar Tanjung to strengthen his own position as party chairman and increase Golkar's influence.

Golkar's leadership Monday freely admitted its decision was a display of realpolitik as party executives looked to cash in on Megawati's "more attractive" offer of ministerial posts and senior regional positions.

"It has nothing to do with support for a particular candidate. They just do not want to have a conflict with party executive board," said Golkar deputy chairman Marzuki Darusman, a moderate entity in the party.

"Many of them see the support as a means to advance their political careers." He said Golkar's support for Megawati was "not solid" since some party executives are also backing Yudhoyono or preferred to remain neutral.

Others see the support of Golkar, a political tool of Suharto during his three-decade rule which ended in 1998, as a retrogressive hindrance to Megawati's pledges of reform for Indonesia.

Suratto Siswodiharjo, the head of Yudhoyono's campaign team, described Golkar's decision as a "blessing in disguise". "It defines a clear line between those who want changes for this nation and those who prefer the status quo," he told AFP.