He had undertaken to speak for Catiline when Catiline was accused of corruption on his return from Africa, knowing that Catiline had been guilty.

He did not do so; but the intention, for our present purpose, is the same as the doing.

To have defended Catiline would have assisted him in his operations as a candidate for the Consulship.
Catiline was a bad subject for a defence--as was Fonteius, whom he certainly did defend--and Catiline was a democrat.

But Cicero, had he defended Catiline, would not have done so as holding out his hand to democracy.

Cicero, when, in the Pro Lege Manilia, he for the first time addressed the people, certainly spoke in opposition to the wishes of the Senate in proposing that Pompey should have the command of the Mithridatic war; but his views were not democratic.