By Stephen Kalin and William Maclean
DUBAI (Reuters) - The elevation of Mohammed bin Salman as Crown Prince of Saudi Arabia has ended two years of speculation about a behind-the-scenes rivalry near the pinnacle of royal power, but he still has to win over powerful relatives, clerics and tribesmen.
The 31-year-old favored son of King Salman was already in effect the day-to-day ruler, with sweeping powers over defense, energy and the economy, even though his cousin Prince Mohammed bin Nayef, 57, occupied the more senior job as crown prince.
For two years the meteoric rise of Mohammed bin Salman stirred talk of strains and competition between the two princes, both known by their initials as MbS and MbN.
That all ended on Wednesday when the Al Saud family publicly closed ranks around MbS following his sudden elevation by royal decree. MbN, stripped both of his rank as heir and his position as the veteran head of Saudi Arabia's internal security forces, was among the first to pledge allegiance to his newly elevated younger cousin.
And yet questions remain over how the youthful MbS will consolidate his own network of power and patronage.
Any jostling for power among the hereditary lines of state founder King Abdulaziz al-Saud is carefully hidden behind the ornate doors of royal palaces. Princes are keen to avoid a full-blown internal struggle of the kind that brought down two previous Saudi dynasties in the 18th and 19th centuries.
"We know there's grumbling, we know there is unhappiness but so far everybody's lined up," said Gregory Gause, Gulf expert at Texas A&M University. He added that he did see not any evidence yet of a family "crisis".
Abdulaziz, who founded the Saudi state in 1932 after conquering most of the Arabian peninsula, had at least 45 sons, of whom 36 survived into adulthood. Since he died in 1953, the country has been ruled successively by six of them.
The next king will be the first from the next generation, and there are no formal rules for how to pick a successor from among Abdulaziz's scores of grandsons.
The reshuffle has sparked speculation of late that the octogenarian King Salman could abdicate in favor of his son to ensure the first generational succession in 64 years takes place without a fight.
"There is a very high probability that the king wants to oversee the transition while he is still alive. A big plan of transition is being put in place," said Mamoun Fandy, a London-based analyst of Arab politics.
Moving MbN out of the line of succession sidelines the most powerful member of one of the most powerful lines: the sons of King Salman's older brother Nayef, who ran Saudi Arabia's internal security forces for decades as interior minister, and was crown prince when he died in 2012.
MbN's successor as interior minister is a 33-year-old grandson of Nayef, keeping the internal security forces in the hands of the Nayef line. But with little government experience and few personal networks to call on, the new minister will probably remain beholden to the king and crown prince, analysts say.
Other princes that might once have been seen as contenders include Miteb bin Abdullah, a son of the last king; Khalid bin Sultan, a son of a former crown prince; or Muqrin bin Abdulaziz, the youngest surviving prince of Salman's own generation, deposed as crown prince in 2015.
But any rival's path to bid for the throne is more difficult now that MbN has accepted MbS's ascension.
"The game is lost because MbN is the one who could have resisted. But since he accepted, it would make no sense for Khalid bin Sultan or Miteb bin Abdullah to object," a Saudi observer said on condition of anonymity while discussing the taboo subject. "The Al Saud will not resort to force to settle their differences. It would never happen."
As King Salman has sidelined potential rivals to his son by bringing in technocrats to replace senior princes in the cabinet, Prince Miteb has become the last senior royal in government not closely connected with the king or his son.
Miteb commands the 100,000-strong National Guard, but a former senior Western diplomat said MbS would probably incorporate the National Guard into the Ministry of Defence, effectively sidelining him.
There is no way to know what sort of horsetrading may have gone on behind the scenes leading up to Wednesday's decision inside the Allegiance Council, the family committee charged with formalizing the succession process.
The council, made up of representatives of each line of the family born to Abdulaziz, endorsed Mohammed bin Salman's ascension by a vote of 31 to 3. Most of the powerful lines of the Al Saud family appear to have been rewarded with senior positions.
"No one said yes and left the room empty handed," said the Saudi observer. In addition to the Nayef line keeping the interior ministry, princes from the lines of former kings Faisal and Fahd became advisors to the royal court.
To keep control, say analysts, MbS must deliver on domestic reform promises aimed at weaning Saudi Arabia off oil and also straighten out the kingdom's foreign policy, which includes a costly war in Yemen, heightened tensions with arch-rival Iran and most recently a move to isolate neighbor Qatar.
"If he's perceived as doing a good job, it'll be much harder to mobilize popular opinion against him," said Gause, the Gulf expert.
He must also maintain popularity among the populace and key interest groups. While he appears to retain the confidence of many young people, the forward-looking prince has irked ultra-conservative clerics and tribal leaders while unsettling some businessmen.
Over the decades when the kings were selected from the small pool of sons of Abdulaziz, discord within the family became visible to outsiders only occasionally.
A group of princes in 1964 deposed King Saud in favor of his brother King Faisal, partly out of concern he was trying to establish a vertical line of succession through his sons rather than a horizontal one to his brothers. Faisal was assassinated by the son of another brother in 1975.
Now, however, the power of other princes has been whittled away, diluted over the decades as Abdulaziz's sons produced scores of children and hundreds of grandchildren, making it harder to mount a challenge from within.
"Saudi Arabia of the past used to be ruled by a politburo of elders, of brothers who shared responsibility and one of them stands out as a king," said the Saudi observer.
"Now MbS is the sole leader and everyone in the cabinet is at his service. These are all his servants."
(Editing by Peter Graff)