Heraklia is right to assert that the debate in the Senate (and here) goes to the heast of why Caesar crossed the Rubicon. But what really did he have to fear?

Did he truly fear Pompey? Pompey had arranged Caesar's political wishes, enabling him to stand in absentia for consul. The Law of the Ten Tribunes saw to that. And there was nothing that any of the hard-liners in the Senate could do that would change that: Caesar had been granted the right to stand in absentia, period. Pompey's legions were in Spain, hardly within shouting distance of the Forum. Caesar's own legions were closer, and could easily have been used to assist his election to the consulship. Caesar had ample funds with which to bribe electors, or, if it came to facing prosecutions, jurors. Pompey's reforms of 52 notwithstanding. So what was there to fear from Pompey? The very suggestion is Caesarian propaganda.

Likewise Curio's appeal to the Senate to rely on Caesar's military forces to resist Pompey's overthrow of the Republic. By the time Curio called up this ghost from its grave, Pompey had put to rest any fear that he intended to perform as Sulla's pupil and march on Rome. Pompey had been fastidious in discharging armies, operating within the powers and times prescribed by the Senate in all of his extraordinary assignments from fighting the pirates to managing the corn supply to serving as sole consul. Curio and Caesar should have known better than to raise that specter of the militant Pompey. It was not believable. I would have to say that it shows how desperate Caesar was becoming. It was growing too obvious what he had in mind. It is all Caesarian propaganda.

As to retaining his imperium, even if the Senate had appointed successors in March of 50, when Caesar's terms of command expired, transfer of authority would not have occurred for several months. And as long as Caesar remained outside Rome's walls he would have retained his proconsular imperium. As it stood, the Senate did agree to extend Caesar's command through November 50, simply by agreeing to postpone allotments until that time! Caesar had everything he wanted!

What Caesar needed in order to cross the Rubicon was some justification, which he trumped up through propaganda. But we need not take that propaganda as historical fact. The facts were much different as attested by Caelius' letters to Cicero, Cicero's to Atticus, as well as Dio's and Appian's histories. The propaganda and Plutarch's tale of the falling out between Pompey and Caesar seem to reenforce one another. But all we need to do is to consider Pompey's reaction to Curio's demand that he lay aside his imperium and discharge his armies beforeCaesar. Pompey was furious ... at last! Until then he had held his anger and astonishment at Caesar's demands in check.