While Caesar was just getting underway in his Gallic campaigns, the situation in Rome was initially in his favor.
In 58 BC, Publius Clodius Pulcher, the wild patrician who scandalized Caesar's home just a few years before, now served his term as Tribune of the Plebs. In complete support of Caesar, he enacted new laws granting himself and the populares more power.
In his greatest coup, he forced the exile of his enemy Cicero, who had prosecuted Clodius earlier for his scandalous behavior. Clodius used Cicero's role in the 'murder' without trial of Senators during the Cataline Conspiracy for his own political gain. He also managed to remove Cato from the front and center of Caesarian opposition by sending him off to annex Cyprus. A rivalry with Pompey was also developing, and he intimidated the great man into inactivity through veiled assassination threats.
Clodius' support of Caesar's position wouldn't last long, however. Clodius was drunk with power and had little agenda to support other than advancing his own power. By 57 BC, the efforts of Clodius, and a continuing rivalry brought Pompey and Crassus back to a shaky mutual dislike.
Clodius was instrumental in being a disturbance in the settlement of Pompey's eastern conquests, and his appointment of Cato to Cyprus caused unrest in Egypt. The Egyptian King, Ptolemy the XII fled Egypt and came to Rome seeking Pompey's intervention, but Crassus opposed helping Pompey settle the matter. Additionally, grain shortages for the last three harvest seasons were exceptionally poor.
As a result, the Roman mob was becoming volatile, and Clodius wasted no time in using this to his advantage. He supported armed street gangs to support his cause, while Pompey used the tribune for 57 BC, Titius Annius Milo, to hire gangs of his own as a counter measure.
Pompey and the current Consul, Cornelius Lentulus Spinther, wanted Cicero to return from exile immediately to help stabilize the situation. Though initially defeated, Cicero was finally allowed to return by early summer of 57 BC. It seems that Caesar, now having fallen out with Clodius, made no opposition to this, and possibly could have supported it.
Cicero's actions upon his return, in general support of the Triumvirate, and voting Caesar a 15 day period of thanks for his defeat of the Belgae, seemed to indicate Cicero's gratefulness for the recall. In one show of support, and in order to correct the grain problem, Cicero had Pompey appointed to a 5 year term as Cura Annonae (manager of the grain supply).
Meanwhile, the gangs of Clodius and Milo were running out of control. Politically both men tried to prosecute one another for various transgressions involving the use of violence.
At one trial of Milo, both Crassus and Pompey were present to speak in support of Milo, and Clodius knew the case was lost. However, he used the opportunity to further divide Crassus and Pompey, attacking and heckling Pompey while openly praising Crassus, despite his support for Milo.
Things began to deteriorate further for Caesar when it seemed that his former supporters were joining against him. Clodius and Cicero soon joined with the Optimates of Bibulus and Cato in blaming all the problems in Rome on Caesar's Consulship of 59 BC. His measures while in office were mercilessly attacked, and his command in Gaul was seriously threatened.
By 56 BC, as Caesar was pushing Roman control throughout the entire Gallic province, the political situation in Rome was falling apart dangerously.
In the midst of planning his next steps in Gaul, Britain and Germania, Caesar returned to Cisalpine Gaul and knew he had to reaffirm support within the Senate. Pompey was in northern Italy attending to his duties with the grain commission, and Crassus went to Ravenna to meet with Caesar. He instead called them both to Luca for a conference, and the three triumvirs were joined by up to 200 Senators. Though support in Rome was unraveling, this meeting showed the scope and size of the 'triumvirate' as being a much larger coalition than just three men. However, Caesar needed Crassus and Pompey to get along in order to hold the whole thing together. Caesar had to have his command extended in order to ensure safety from recall and prosecution.
An agreement was reached in which Caesar would have his extension, while granting Pompey and Crassus a balance of power opportunity. Pompey and Crassus were to be elected as joint Consuls for 55 BC, with Pompey receiving Spain as his province and Crassus to get Syria. Pompey, jealous and likely concerned over Caesar's growing army, wanted the security of a provincial command with legions, and Crassus wanted the opportunity for military glory and plunder to the east in Parthia.
With the matter resolved, Crassus and Pompey returned to Rome to stand for the elections of 55 BC. Despite bitter resistance from the optimates, including a delay in the election, the two were eventually confirmed as Consuls.
Caesar took no chances however, and sent his Legate, Publius Crassus, back to Rome with 1,000 men to 'keep order'. The presence of these men, along with the popularity of Crassus and Pompey, went a long way to stabilize the situation. The gang wars of Clodius and Milo relaxed for a time, and Cicero relaxed his outspoken opposition.
However, almost as soon as Crassus left to govern his province in late 55 BC, Pompey's inability as a politician began to show. With Pompey handling the situation alone, things soon began to unravel and he would be forced ever closer to the optimates in order to maintain order.