Special counsel Robert Mueller wants to talk to the president. With the pitched battle of words forever escalating—Trump’s new team of gloves-off lawyers and his vocal supporters pitted against the special counsel’s own proponents in the media—many exude confidence in Mueller’s power to subpoena the president’s testimony, assuming the eventual backing of the Supreme Court.

But let’s slow down a bit. Although Mueller has warned Trump’s lawyers that he might subpoena the president if he refuses to testify voluntarily, he might well elect not to. The two sides could compromise on a deal for testimony on limited subjects or only in written interrogatories. Or Mueller might see the risks, delay, and other costs of starting a subpoena battle as outweighing the benefits—especially if the evidence he has gathered does not clearly implicate Trump in any serious crime. Mueller’s risk in starting a subpoena fight is that he might win less in the Supreme Court than he could have gotten in negotiations, or even lose entirely.