That's the charge opponents level. And the one some Senate Democrats are said to fear most.
But to restate the case against that position, I'll borrow from a Congress Matters post from July:
What troubles, specifically, do we think Democrats might face if the rules changed when Dems had a smaller majority, but still a majority?
Would Democrats' political opponents claim their power was somehow illegitimate? That they ought to be thrown out of office on some imagined technicality? That they were conducting some sort of illegitimate power grab in order to force through a radical or even socialist agenda?
Oh no! I hope we never have that happen!
On a slightly more serious note, I have to ask whether it would be OK for Republicans to one day make this change based simply on retaking the majority, or whether they and Democrats both would have to wait until there was once again a majority of the size Democrats had in this Congress? How big must a majority be before it feels comfortable changing the rules?
I think you probably see where I'm going with this. We're headed toward imposing a supermajority requirement for getting rid of the supermajority requirement -- which is to say that reform would be impossible.
In other words, the charge of "power grab" will come just as surely no matter how many seats Democrats have in the Senate. In fact, I submit that the charge would have been made even more sharply had Democrats attempted to change the rules at the beginning of the 111th Congress, with 58 seats. I imagine the complaint then would have been something along the lines of, "Democrats propose an agenda so radical, they can't themselves imagine persuading just two Republicans to join them!" Or, "They can't even hold their own caucus together, and they're changing the rules so they can still pass their radical agenda even when they lose eight of their own votes!" Whatever they thought could possibly stick, Republicans would have been throwing at Dems. You know it's true.
So instead, we're seeing them throw it at a Democratic caucus of just 53. Not because it's any more or true, but because it's all they have, and they think it just might work.
More from July:
This is not to say that it's flatly invalid to raise concerns about the political optics of pursuing reform with a narrower majority. But I think it's fair to ask how big a majority should have to be, and whether the numbers would be the same for Republicans as it appears to be for Democrats. And if it's not strictly a numbers thing, then how should we judge whether the correct signals have been sent? And finally, if we're not all that confident that Republicans would pause to weigh the political optics of reform should they regain the majority, how much time should Democrats invest in worrying about it themselves?
Offhand, I'd say there's more to be confident about in the political optics of doing something than there is in hoping to be rewarded for your forbearance.
There is no number of seats a majority can have that would prevent the minority from charging them with a "power grab." It's simply not a problem worth contemplating. It will happen no matter what your numbers are, or who does it. But then again, though the party that does it will have to live with the consequences -- if there really are any -- of being hit with the "power grab" attack, they will still, in the end, be the party that got it done. And that will be what matters on the day after the political points from the attack are scored.