Cassius would succeed as a politician this day and age and would likely make it all the way to president. He is ambitious and unafraid to cross any lines. He's willing to sell out his morals and his beliefs for the support needed to obtain his position. He is the example of the politician who says won thing in his campaign, but does the opposite while in office.
Brutus would be a good leader, but he would never get elected. His honesty would stand in the way of his popularity. He would speak truths rather than twisting things to serve his purpose and get the voters on his side. He would not align himself with special interest groups offering him financial support in exchange for a favor once in office. I could see Brutus as one of those fringe third party candidates who have some loyal supporters; however, unfortunately, those supporters are far too few in number.
I concur witih marilynn07 that Cassius would fare better in the arena of politics than Brutus. If there were a comparison to presidents of our modern times, Brutus would, perhaps, be like Jimmy Carter, who also was so committed to principle. Unfortunately, however, he did not fare well in economics or many foreign affairs. He was, like Brutus in his battles, inept and ineffective During his presidency the attempt to free the Iranian hostages was an embarrassing failure, and there was double-digit inflation, so conditions in foreign and domestic affairs were worsened, not improved. Cassius, like Richard Nixon, has the political acumen to recognize proper strategies, but he argues with Brutus and cries that Brutus no longer loves him in one scene, a scene reminiscent of some of Mr. Nixon's emotional breakdowns. Like Nixon, Cassius could be an effective politician, but his defective personality, also, defeats him.
Cassius is manipulating and sly. He would fit in just fine in Washington with our current bunch.
Brutus, even though he is noble and does what he thinks is right for Rome, is naive. He is gullible and allows people with ulterior motives to sway him to do something he doesn't feel good about...he would be fed to the wolves, unless he could learn to stand on his own feet and make decisions that were sound. I am reminded that what is popular is not always right, and what is right is not always popular. Brutus would either fail as a politician because he followed the wrong group, or he would succeed in small-time local government without moving up the proverbial totem pole.
This is an interesting question.
Cassius is ambitious and power hungry. However, he is probably too moral for the present bunch of politicians. He would I think be able to assimilate into the mix and be just like the rest of the politicians in short order. Cassius would probably easily cast off his morals in favor of prestige and power. He would be the person who gains the favor of the "right" people to help him secure a position of power.
Brutus is another story. I think Brutus did what he did based on his beliefs on saving the Roman Republic. He is not "power-hungry" like Cassius, but highly forthright and moral. Brutus joined the crowd to do harm to his benefactor but only after weighing all of the options carefully. I think he would be a successful politician in today's climate, but not one that rises to a high or totally powerful position. Brutus' morals will hold him back.
I would say not very well in this day and age. They clearly have too many faults and both are unable to either trust their own instincts or anyone else's because they have such a poor ability to choose friends wisely.