The endurance of John F Kennedy's memory, when that of other US presidents has faded, is only partially explained by the manner of his death, of a charismatic leader cut down in his prime and the thought of what might have been. Kennedy carried with him the hopes of a generation, but the mood of America then has few parallels today. It was optimistic, internationalist and, by today's standards, illiberal. Had he lived, what JFK might have done on civil rights, the defining struggle of his decade, is a matter of debate. He lacked Lyndon Johnson's understanding as a southerner or his sense of urgency. Public opinion at the time thought JFK was pushing too hard, too fast.

Like Kennedy, Barack Obama also started out as a genuinely inspirational president. His list of achievements, however, must all be qualified: on the one hand, the withdrawal from Iraq and what will become a partial pullout from Afghanistan; on the other, a commander in chief who has ordered more drone strikes than any other, and presided over the most intrusive internet and telephone surveillance operation ever. Mr Obama's liberalism is directional. Step out of the allotted vectors of progressive action and this president turns out to be flawed in his own ways. The Affordable Care Act is a huge achievement – if they can actually get it to work. But Mr Obama's White House can not be understood without factoring in the conservative forces determined at all costs to stop this administration from working.

The right's horror towards Senate Democrats' move this week to end the filibuster for most nominations by presidents must, for instance, be weighed against the frequency with which that wrecking ball has recently been swung by Republicans. As the Senate majority leader Harry Reid said, half of all the filibusters in the history of the republic occurred in the last five years. Further, 20 of the 23 district court nominees filibustered in the history of America were nominated by Mr Obama. Were they so unfit for office? Patently no. Were Republicans in the Senate so intent on obstructing everything that emanates from this presidency? Patently yes. So the "nuclear" option of banning the filibuster has to be judged against how irradiated the atmosphere in Washington already is.

There are valid arguments to be had about changing a legislative chamber which has afforded more rights to its minority than any other in the world. Judicial appointments are for life so, unlike legislation, judges cannot be repealed by the next administration. There are, too, concerns about how Republicans would behave if the tables were turned. The move marks the formal end of a policy that featured large in Mr Obama's first term of office – the search for bipartisan solutions. But let us face it. That search was doomed from the start. He was rightly criticised for feeding the crocodile: when you run out of chickens to throw it, it takes your arm.

The problem with high-minded reflections on the partial end to the filibuster is that it was nothing more than an effective political tool. Without it, America would now have the legislative means to curb its carbon emissions. The Affordable Care Act would have had a public option to curb the excesses of private health insurance companies. Without it, Mr Obama would not have had to file down the tip of many of his arrows. Republicans cannot complain about the political nature of the Democrats' move, without acknowledging how politically they behaved in the first place.

Of course, their mandate is to oppose. How they do it, however, is their responsibility. The cure for Republican extremism is a substantially reduced mandate in the mid-term elections next year from an electorate fed up with their actions in Congress. Only once they have been brought low will the Republicans, paradoxically, become electable again.