During nearly five decades in power, Syria's Baath Party has evolved from an Arab nationalist movement into a vast organisation that has infiltrated every aspect of public life.
When Hafez al-Assad seized power in a coup in 1970, the party became a vital tool to instil loyalty, as well as help control the government and military alongside the pervasive security services.
The party's senior leaders have remained loyal to the late president's son, Bashar, despite a call from the main opposition coalition, the Syrian National Council (SNC), for them to defect in protest at the violent crackdown on anti-government protests that began in March 2011.
The Baath Party was founded in 1947 by Michel Aflaq, a Syrian teacher, whose brand of radical Arab nationalism won supporters across the region.
The party's early slogan "unity, freedom, socialism" attracted a generation of Arab political activists who wanted to overthrow the European-backed governments of the Middle East and create a modern industrial economy.
In 1953, the Baath Party merged with Akram Hawrani's Arab Socialist Party to become the Arab Socialist Baath Party. The shrewd alliance helped the new group quickly become a serious challenge to its rivals.
However, it was army officers who played the leading role in establishing Baathist rule. Hafez al-Assad was among a group of Baath supporters in the Syrian army who seized power in 1963.
Growing disagreements between the civilian Baathists, such as Aflaq, and the party's Military Committee, led by young officers such as Assad, caused a split in the pan-Arab movement.
Aflaq's supporters were forced from the Baath Party leadership. They found refuge in Iraq, where the Baath Party returned to power in a coup in July 1968. The Iraqi Baathists elected a new pan-Arab leadership, which included Saddam Hussein and Aflaq.
After Hafez al-Assad launched his own coup in Syria in 1970, dubbed the "Corrective Movement", the rift between the rival wings of the Baath Party deepened. A Syrian court condemned Aflaq and other veteran Baathists to death, after trials held in their absence.
In 1973, the Syrian constitution was amended to give the Baath Party unique status as the "leader of the state and society", ushering it into all areas of public life.
Its main role was to issue directives from the central government to regional representatives, mobilise the masses for political activities, and gauge the "mood" of the general population.
Children were indoctrinated with the party's ideology at school, Baathists controlled trade unions, and the Military Committee monitored the armed forces.
Many posts in the public sector, the military and government were generally reserved for Baathists, which helped boost party membership. By 1981, some 375,000 people had joined the party. By 2010, this number had reportedly risen to 1.2 million - nearly 10% of the population.
The only other legal parties were from the National Progressive Front (NPF) - an alliance of nationalist and left-wing supporters of the government who accepted the Baath Party's "leading role".
Baathist officials were, however, targeted during an armed insurrection by Sunni Islamist groups in the late 1970s and early 1980s, which culminated in a rebellion in Hama in February 1982 that was brutally crushed, leaving between 10,000 and 25,000 people dead.
Over the next two decades, the Baath Party remained hugely influential, but real power was increasingly collected in the hands of President Assad, his family, close advisers, the military and security services. Despite this, in the eyes of many Syrians the party embodied the corruption, nepotism and stagnation that became so widespread.
When he was elected president and chairman of the Baath Party's Regional Command in 2000, Bashar al-Assad sought to present himself as a reformer.
Ahead of a rare Baath Party regional conference in 2005, state media talked of an opportunity for the party's "revitalisation". But expectations that the constitution would be amended to remove the article making it the leader of state and society were never met. The political party law was also not changed to permit the existence of groups outside the National Progressive Front.
In fact, it was only in February 2012, after nearly a year of anti-government protests and bloodshed that threatened the dominance of the Assad family and the Baath Party, that the constitution and the political party law were changed.
They did not, however, have much of an impact at the subsequent parliamentary elections in May, which were boycotted by the opposition and saw pro-government parties win almost all the seats.
At the start of the uprising, a large number of officials publicly left the party in protest at the government's suppression of dissent. And in March 2012 the then Deputy Oil Minister, Abdo Hussameddin, announced his defection to the opposition.
Such incidents gained a great deal of coverage in the world's media, but the Baath Party officials involved were appeared to be relatively minor.
The party's main leadership bodies, the Regional Command and the National Command, have remained steadfastly loyal to Bashar al-Assad.
Analysts say top officials in the Baath Party lead a privileged life, and stand to lose the most from a change of government.
Many also belong to Syria's minority groups, including the president's own Alawite sect, and see the uprising as a struggle for survival.
It therefore seems unlikely that Baath Party leaders will abandoned the president in the near future, regardless of the increasing international pressure and rising death toll.