“If it isn’t over by September,” Rudy Giuliani tells Sean Hannity about the Robert Mueller investigation, “then we have a very serious problem.” Best guess: They’ll have a very serious problem. Donald Trump’s legal team sent a counterproposal back to Mueller regarding an interview with their client earlier in the day, attempting to take topics completely off the table — and then going on TV with Sean Hannity to call the whole investigation corrupt.

“Why would you even consider a counterproposal?” Hannity wondered after Giuliani called the special counsel probe “a different kind of Watergate.” Giuliani smiled and replied, “When it’s over with, I’ll explain it to you.” Hopefully someone will:

So what about the counterproposal? Giuliani sent the letter off to Mueller yesterday, indicating that the president would still consider sitting down with investigators. However, Giuliani told Axios that Mueller would have to promise not to bring up two topics:

The former New York mayor told Fox News’ Sean Hannity in an interview last night that the investigation should be “over by September,” and that Mueller’s case “isn’t going to fizzle. It’s going to blow up on them.” He added, “[T]here’s a lot more to what they did that nobody knows about yet … a lot more to the obstruction of justice, to the collusion, to the fake dossier.”

Giuliani told Axios that there are two topics the president’s lawyers want to rule out in order to agree to a Trump sit-down with Mueller:

• Why Trump fired FBI Director James Comey.
• What Trump said to Comey about the investigation of former national security adviser Michael Flynn.

Other than that, Mr. Mueller, how did you like the obstruction? Trump’s legal team wants to screen off any possibility that their client will incriminate himself in an interview on those subjects. They’re apparently entirely sanguine about the Russia-collusion hypothesis being a dead end, but obstruction is an easier target for wily prosecutors. It doesn’t take much to set up a perjury trap, especially when dealing with a target with a mouth as famously undisciplined as Trump. Taking Comey and Flynn off the table closes off any path to obstruction … which is why Mueller’s not about to buy off on those terms.

Which brings us back to Hannity’s question: If it’s so corrupt as to be a “Watergate on the part of the investigators,” why cooperate at all? For that matter, why not order Rod Rosenstein to shut it down? The political damage would be too great, of course, but the offers of cooperation are undercutting the attacks on Mueller and the investigation. At some point, most Americans will conclude that it’s just spin, even if the underlying allegations don’t amount to much so far.

The other possibility is that Giuliani & Co want to run out the clock on Mueller. Giuliani tried arguing in this segment that the upcoming midterm elections present a hard deadline for Mueller, which he’s been arguing for the last several months without much merit. Supposedly, the DoJ’s guidelines discourage investigative activity within 60 days of an election for someone running, but Trump’s not running and no one paid attention to those guidelines in either direction in 2016. Like any other special counsel investigation, Mueller’s is completely open-ended without any deadlines except those which he sets for himself.

That’s a good reason to refrain from appointing special counsels in the first place.