The adjective "accountable" is more specific than "responsible": you can be legally responsible without being accountable or being very little accountable because nobody or no body is actually able to ask you to account for your actions with effectiveness.
So "accountable" is when you are actually held responsible for your actions because somebody or some body is actually able to force you to take responsibility for your actions and, because you are aware of that, you avoid misbehaviours and do your best to actually behave with responsibility.
This is not your virtue, it is a necessity due to the way a system works (and it has different degrees of effectiveness, it is not just an abstract legal notion).
In Italian no adjective renders this notion. In my personal opinion "responsabilizzato" is the closest term (definitions from Treccani and Corriere): it is when you are made responsible for your actions (or trained to behave with responsibility). So you could say: «Sono la componente meno responsabilizzata del ceto politico».
Otherwise you would need a longer expression as «Sono la componente del ceto politico dotata di minor senso di responsabilità ed affidabilità». "Senso di responsabilità" would render the self-awareness that is implied in the notion of accountability. "Affidabilità" would render the effectiveness of your responsibility.
I will look into it further for evidence in support of the opinion expressed above. This is one. This is another. This in the army. On Google Scholar you can find lots of published studies where the words occur. Some sources suggesting the word cannot be directly translated in Italian: 1, 2, 3, 4.
EDIT: following doubts in the comments, I have collected a quite large sample from The New York Times and The Economist which should convince anyone that the two adjectives, "accountable" and "responsible", are not interchangeable:
- «If not accountable, let's hope they are at least responsible»
- «Hold me accountable for the debacle. I'm responsible»
- «Governments which are not accountable to their subjects are, strictly speaking, not responsible. They are irresponsible»
- «It reminds them that they are part of a community that requires them to be responsible and accountable for their behavior and acts»
- «Make government employee and politicians responsible and accountable»
- «You are personally responsible for your own actions and accountable for your own actions»
- «John Deutch, the Director of Central Intelligence, has responded to the Guatemala case with admirable determination to make the C.I.A. more responsible and accountable»
- «He is responsible (and accountable) for the performance of more than a dozen agencies involved in foreign intelligence collection and analysis»
- «It is a system which casts the mayor as an outsider who is neither accountable nor responsible for the performance of perhaps the most important municipal activity»
- «… the onus of policing social policy and protecting the environment is on local governments, and it is local policy makers who should ultimately be held accountable and responsible if and when egregious failures occur»
- «In 2005, the Bush administration wisely challenged China to become a responsible stakeholder in the international system and to make its government responsible and accountable to its people»
«The World; Accountable, Responsible or Something in Between»
«The international community has a moral and political responsibility to hold accountable those responsible»
- «The voters are unable to throw the bums out because there is no means of holding accountable those who are responsible»
- «I want to know when my government is misbehaving. These sorts of leaks are the only way that those responsible can be held accountable»
- «The best hope of getting responsible decisions by technocrats on their technologies is to make them personally accountable»
- «The question is no longer who is responsible. The question now is whether they will be held accountable»
- «Mr Obama promised that if banks need more aid, “we will hold accountable those responsible”»
- «He said his ultimate goal was to hold accountable those responsible for Syria's destruction»
- «Yes, the I.R.S. made egregious mistakes and those responsible should be held accountable»
- «If this is true, there should be an investigation and those responsible held accountable»
- «Those responsible for CAR violence must be held accountable»
- «This wanton killing and maiming should be stopped and those responsible held accountable»
- «Attorney General Eric H. Holder Jr. promised Tuesday that federal officials would work to hold those responsible accountable»
- «Our investigation remains active in the expectation that we will ultimately hold accountable the person responsible for this crime»
- «The F.D.I.C. brings this complaint to hold these highly paid senior executives, who were chiefly responsible for WaMu’s higher-risk home lending program, accountable for the resulting losses»
- «There will be proposals for ways to prevent these rare, devastating events and for holding responsible parties accountable»