A planned wave of protests over disputed Malaysian elections is the most provocative challenge to the government in years, upping pressure on a long-ruling regime already smarting from the polls.
Opposition leader Anwar Ibrahim offered a preview of the movement's potential Wednesday when he rallied a huge display of citizen power in Kuala Lumpur estimated to number up to 100,000 people.
Anwar says his opposition will push a nationwide campaign to dispute last Sunday's election in which it won a majority of the popular vote but still lost to the 56-year-old government, which he accuses of massive electoral fraud.
Any move to overturn the result looks doomed to fail, with the opposition accusing the Election Commission and courts of being in the government's pocket.
But the drive could lead to instability in the multi-ethnic country if Anwar, who has battled the Barisan Nasional (National Front) government for 15 years, can deliver promised "proof" of fraud, said pollster Ibrahim Suffian.
"If the opposition can produce meaningful evidence of fraud, the government may fall into a crisis of legitimacy," said Ibrahim, who runs independent opinion researchers Merdeka Centre.
That would further squeeze Prime Minister Najib Razak, whose standing in the United Malays National Organisation (UMNO), the power behind Barisan, is less than clear.
Besides losing the popular vote, the coalition ceded a number of parliamentary seats, prompting speculation over whether Najib would face a leadership challenge in party elections by year-end.
In much-analysed comments after the election, influential former hardline leader Mahathir Mohamad expressed disappointment with Najib's performance.
"Of course, the people will question his capacity and his strategies," Mahathir said, adding "the party may take action, as happened with Abdullah".
He was referring to former premier Abdullah Badawi, who was dumped by UMNO following a weak 2008 election showing, in a party putsch spearheaded by Mahathir that brought Najib to power.
Barisan, which is dominated by ethnic Malays, has controlled parliament for decades while a small and ineffectual opposition has largely looked on.
But Barisan, accused of corruption and authoritarianism, suffered unprecedented losses in 2008 to its reform-minded rivals, prompting Najib to subsequently woo disaffected minorities in a bid to win back support.
That appears to have failed, with the nation's economically powerful Chinese, who make up 25 percent of Malaysia's 28 million people, rejecting his government in unprecedented numbers Sunday.
Najib poured fuel on the fire after the election by appearing to blame Chinese for his disappointing showing.
"We are more polarised and fragmented than ever," political scientist Faisal Hazis said, adding that Najib faced a "dilemma" in healing the divisions.
A key factor for the polarisation is Barisan's longtime use of race politics, and in particular, advantages given to Malays in business, education and other spheres.
The policies irritate minorities and are blamed for a brain drain and curbing national competitiveness.
Najib has made limited reforms, but Faisal said only dumping the system outright was likely to win back voters including middle-class Malays who feel the policies mainly benefit a Malay elite.
"Najib has lost their trust. Only a big gesture can win them back," Faisal said.
Analysts said Najib also may need to head off questions about his legitimacy by addressing problems in the electoral system, which had already sparked massive demonstrations in recent years.
But though Najib has called for an effort to heal the widening political and social schisms, analysts say that will be difficult as he must appease UMNO conservative forces who already have lashed out at voters who abandoned Barisan.
Such forces are more used to "retribution rather than reconciliation", said Ibrahim. "This means reforms will have to take a back seat."
Najib, however, is believed well-placed to ride out any leadership challenge, which analysts said would only play into the opposition's hands.
"If there was an attempt to challenge Najib, it could cause the government to collapse as Anwar is ready to pounce," said Mustafa Ishak, politics head for the National Council of Professors.
UMNO parliament member Nur Jazlan Mohamed told AFP that Najib has already briefed coalition members on plans to refocus government resources on cities, where many of the most disaffected voters are, in a bid to win back support.