* Opposition leader Capriles challenging results of vote
* Maduro has less power to control Chavez's disparate coalition
* Weak mandate may dampen foreign aid and aggressive foreign policy
The bereavement of millions of Venezuelans at Hugo Chavez's funeral last month appeared to signal that the political movement he led would remain strong long beyond the passing of its inspirational founder.
Just six weeks later, however, his anointed successor barely scraped out a presidential election victory over opposition candidate Henrique Capriles, who was roundly defeated by Chavez just over six months ago.
Nicolas Maduro's narrow election win suggests that "Chavismo" - the political philosophy and disparate coalition built up by Chavez during 14 years in power - will struggle without him.
Maduro clearly does not have his charismatic predecessor's command over the OPEC nation and may face challenges from rivals within the Chavista ranks.
"These results require deep self-criticism," said Diosdado Cabello, the powerful head of the National Assembly, another close ally to Chavez whom many see as a potential rival to Maduro.
"Let's turn over every stone to find our faults, but we cannot put the fatherland or the legacy of our commander (Chavez) in danger."
Chavez beat Capriles by 11 percentage points in October for his fourth presidential election win and that was after a long campaign in which he was severely weakened by the cancer that killed him on March 5.
His death unleashed a wave of emotion that immediately boosted Maduro's poll numbers, suggesting he would stroll to victory. His campaign was also boosted by ample state resources and unlimited access to government-run television outlets.
But his lead faded fast in the last days of the campaign and his winning margin was just 1.6 percentage points. Capriles, who quickly conceded defeat against Chavez in October, is bitterly challenging the result from Sunday's election and demanding a full recount.
To be sure, millions of Venezuelans stayed faithful to Chavez's dying wish that they back Maduro and many will continue to support him.
He enjoys control over the courts and state prosecutors, and few believe the electoral authority would overturn the results of Sunday's vote despite the opposition's allegations of irregularities and demands for a full recount.
But the close and contested vote means Maduro now has less room to carry on Chavez's six-year campaign of nationalizations or advance a utopian and controversial plans that include the creation of "socialist communes" which would compete with state and local governments.
He may also have more limited capacity to follow Chavez's foreign policy goals, including generous assistance to Cuba and other left-wing governments in Latin America, the constant excoriation of Washington, and high-profile support for U.S. pariahs such as Syria and Iran.
CHALLENGE FROM WITHIN
Chavez burst onto Venezuela's political scene by leading a failed coup in 1992, electrifying the nation with a brief televised speech in which he admitted defeat "for now."
After serving time in prison, he launched his political career and swept to power in 1998 on a leftist platform.
During his 14-year rule, Chavez crafted a top-down system that allowed him to steadily concentrate power by controlling state institutions, while demanding unswerving loyalty from his protégées.
Bolstered by his personal magnetism and fear of his ferocious temper, Chavismo has attracted supporters as disparate as military officers and oil executives to armed slum organizers and socialist intellectuals who often have little patience with one another.
While Chavez's repeated trouncing of adversaries at the ballot box let him effortlessly brush off any questioning of his democratic credentials, Maduro's narrow win means he will start his term in office from a much weaker position.
Cabello was long seen as a more experienced manager than Maduro, but also generally perceived as less likable and more vindictive. Chavez in December passed him over as successor in favor of the mustachioed former union organizer.
As head of the country's Congress, Cabello will likely try to boost the power of a legislature that was weakened steadily during Chavez's time in office. He has considerably greater sway than Maduro in key power blocs including the military and state governorships that are crucial in ensuring the wealth from oil resources reaches poor Venezuelans.
While Chavez marked his election victories by whipping crowds of supporters into a frenzy, many supporters at Maduro's victory speech on Sunday wandered aimlessly back and forth as he talked, checking phone messages and dejectedly pondering why the results were so much tighter than expected.
"Without Chavez, he (Maduro) will have no capacity to ask that the population be patient while he fulfills promises and meets expectations," said local pollster Luis Vicente Leon.
Opposition sympathizers pointed out via Twitter that after weeks of calling himself a "son" and "apostle" of the messianic socialist, Maduro now looks more like a distant cousin.
Any division within the leadership of "Chavismo" could promote a splintering of the various groups that no longer have Chavez's charisma - or his iron hand - to keep them together.
Maduro also faces a weakening economic panorama of slower growth and higher inflation following a binge of government spending in 2012 that helped ensure Chavez's re-election victory but left state finances strained by debt.
Maduro's reputation for moderation and capacity for dialogue has led many to believe he could seek more pragmatic economic policies to address problems such as nagging product shortages. This would be considerably more difficult in the context of internal dissent and softer public support.
"Though Chavismo could have seemingly won this election, the sustainability of this political movement, which was always centered around the personality of President Chavez, could face serious challenges in the longer term," Barclays analysts said in a research note.