The terms of the trade aren’t surprising. Bolton and Biden will obviously be the first two witnesses called, if witnesses are called.

What’s surprising is Toomey’s involvement. He hasn’t been mentioned in any of the coverage of the witness conundrum Senate Republicans are facing. It’s always Collins, Murkowski, and Romney, with Lamar Alexander maybe possibly conceivably a very reluctant 51st vote. Alexander doesn’t want to be known as the man who made John Bolton’s testimony possible; he’d like to have a 52nd vote (and a 53rd, 54th, 55th, etc) to give him a little cover.

Is Toomey the 52nd? More importantly, is he willing to be the 51st if Alexander gets cold feet?

Toomey has confided to GOP senators that proposing a “one-for-one” deal with Senate Democrats may be necessary at some point, particularly with pressure mounting for witnesses to be called, according to the officials, who requested anonymity to discuss private conversations. He has argued that such an arrangement could force Democrats to accept a Republican witness against their wishes or else risk having Republicans move ahead to acquit Trump, the officials said.

Toomey has spoken about his idea with Sen. Mitt Romney (R-Utah) and others, the officials added…

Separately, two Senate GOP aides, who requested anonymity to speak frankly, said Romney is in touch with Toomey and generally supportive of a witness deal that he believes is fair to the GOP but has not yet signed on to any specific plan.

The proposal also came up in private conversations at Monday’s closed Senate GOP lunch, according to the officials and a Senate aide briefed on the meeting.

McConnell is reportedly cool to the idea, urging Republicans not to make any commitments until they formally take up the issue later this week. That’s the prudent thing to do — play for time and hope that maybe Bolton will have a change of heart or say something discouraging about his testimony. If he were to put out a statement accusing the Times of distorting what his manuscript said, for instance, maybe that’s enough cover for Senate Republicans to shrug and say, “Guess we don’t need to hear from him after all.”

It makes sense to find Toomey trying to swing a deal on witnesses, meanwhile, since he’s a compromiser by nature. His bipartisan bill with Joe Manchin to expand background checks has been the leading Senate proposal on that issue for years now. He’s also facing reelection in Pennsylvania in 2022, which could be difficult if Trump wins reelection this fall. The out-party tends to perform well in midterms and Toomey’s seat will obviously be a prime Democratic target, as he’s survived not one but two razor-thin Senate elections. In 2010 he won by two points, buoyed by the Republican wave that year. In 2016 he won by a point and a half, buoyed by Trump’s victory. Whether he can win a race in PA when the political winds are blowing in on him rather than at his back is an open question.

So he’s hedging his bets. He’ll vote for acquittal in the end, but if he can show a little independence by brokering a Bolton-for-Biden deal — potentially pleasing to the bases of both sides — then why not do it?

The wrinkle is what happens if either Bolton or Biden or both give testimony that implicates others to some greater or lesser degree. I shouldn’t even say “if”; unquestionably, each man will say something that the opposing party wants to explore by calling secondary witnesses. How does the Toomey one-for-one deal work in that circumstance? Some witnesses are better than no witnesses, politically speaking, but if Bolton accuses a number of people in Trump’s inner circle, it’ll be hard for Collins and the rest to shrug at that point and say, “Let’s skip ’em and wrap this up.”

Maybe executive privilege would bail out the president in that case. Mulvaney and Pompeo can’t be called, the White House would say, because they’re still on staff at the White House, unlike Bolton. Possibly that’s enough of a reason/pretext for Collins and the rest to shut down the witness phase and proceed to deliberations and acquittal.

One remaining longshot possibility: Bolton could be blocked from testifying somehow, possibly via a drawn-out court battle between the White House and the Senate over his subpoena (although the optics of that would be bad at this point), and meanwhile he could voluntarily silence himself by not publishing his book as scheduled. Fred Fleitz, who worked for Bolton at the White House, has an op-ed out today urging him to do that.

If a manuscript of this sensitivity was to be published at all, this should happen after the election, not in the spring of 2020. I don’t understand the need for a former National Security Adviser to publish a tell-all book critical of a president he served, especially during a presidential reelection campaign that will determine the fate of the country. There will be a time for Bolton to speak out without appearing to try to tip a presidential election.

Former Secretary of Defense Robert Gates, who stepped down in June 2011, published a devastating book titled “Duty: Memoirs of a Secretary at War” that detailed the incompetence of Vice President Joe Biden and the Obama National Security Council staff. But because he did not want his internal knowledge of the workings of the Obama administration and his interactions with President Obama to affect the outcome of the 2012 presidential election, Gates did not publish his book until January 2014.

Gates established a principled precedent on how senior advisers to presidents should write about their experiences. Given Ambassador Bolton’s long and distinguished record of government service, I believe it is vital that he follow this precedent.

I can understand thinking a former advisor should hold his tongue during an election year over policy disputes with the president he served out of respect for his former boss. I’m less understanding of thinking he shouldn’t reveal incompetence by the administration, as that’s something voters should know before they vote. I’m less understanding still of thinking he should hold back potentially incriminating evidence about a president who’s on trial in the Senate. We don’t want advisors gratuitously kneecapping the commander-in-chief to sell a book but we also don’t want the electorate choosing presidents based on incomplete information about whether they did or didn’t try to swing a quid pro quo with a foreign government to damage the other party’s nominee. If the DOJ had probable cause to believe that Trump or Joe Biden or Bernie Sanders was engaged in some sort of ongoing crime right now, does Fleitz think that information should also be suppressed lest it influence the vote this fall?

It should influence the vote this fall, no?

Here’s future Trump chief of staff Mark Meadows noting, perfectly accurately, that there’ll be political consequences for Republican senators if they vote against Trump on impeachment. When Adam Schiff made that same point a few days ago, albeit by borrowing more colorful language, the GOP caucus claimed it was appalled.