A lot of Senate Republicans object to the nomination of Matt Gaetz to be attorney general — up to 30, according to an unnamed source in the Wall Street Journal — but aren’t saying on the record that they object. Several motives for their silence can be inferred. Some of them may think that President-elect Trump deserves a lot of deference for his selections, especially after a solid election win. Some of them may worry that an early defeat at the hands of a Republican Senate would undermine the new administration at its start. Some may think that Gaetz deserves a hearing — or, at least, that it would look bad to reject him without giving him one.

But it’s likely that another motive looms larger. Republican senators know that if they come out against Gaetz, Trump and some of his supporters will attack them for their disloyalty. Such attacks might lead to serious primary challenges.

The resulting incentive for these Republicans is to wait. Maybe some revelation will lead Gaetz to withdraw, or Trump to withdraw the nomination. (This scenario seems unlikely, given that nothing already in the public record has fazed Gaetz or Trump.) Or maybe enough other Senate Republicans will vote down the nomination so that some opponents can vote for him, letting them stay on Trump’s good side secure in the knowledge that Gaetz won’t be AG.

There are two drawbacks to this approach compared with, say, a public declaration of opposition, today, from ten Republican senators. One is that keeping quiet might end in Gaetz’s confirmation, which these senators don’t want. Time tends to mute outrage. The other is that if Gaetz is eventually defeated anyway, the political damage to the Trump administration and the time wasted will be greater.

If all 30 of the supposed objectors went public, the scope of possible retaliation from Trump would be smaller, too. Those senators presumably think that Trump himself would be better off, in the long run, if some limits were placed on his willfulness. But there’s a collective-action problem, and Republican senators are not good at solving those.