According to John Bolton’s book out Tuesday, it’s fair to say President Trump’s former national security adviser agreed with Democrats that Trump politicized foreign policy for his own gain. Bolton claims Trump did so on multiple occasions.

Bolton writes that Democrats committed “impeachment malpractice” for not investigating beyond Ukraine and says Trump asked China’s president for help, too. But at the time, he refused to testify willingly or even with a subpoena.

Now Democrats have to decide again whether to have Bolton testify on what he knows. It could risk looking like overkill after they already impeached Trump for his Ukraine work. But if they don’t have Bolton testify, they could come across as if they are looking the other way on allegations that are arguably more serious than what they impeached Trump for.

There’s a lot of history that could inform their decision. So let’s look back at why Bolton didn’t testify in Trump’s impeachment trial in the first place.

Why Bolton said he didn’t testify

Bolton says he thought Democrats were being partisan and he didn’t want to participate in that.

Partisanship probably framed Bolton’s view on this, too. Bolton would have been the highest-profile person to testify, and his testimony would have been significant. He had already left the Trump administration at the time of the impeachment investigation in the House, but he was involved in a number of meetings and conversations around Trump’s dealings with Ukraine. Bolton could have been the linchpin in Democrats’ investigation.

And that would have made him the protagonist in Democrats’ impeachment inquiry. That didn’t seem like a partisan picket line that Bolton, who has dedicated his career to conservative foreign policy, was willing to cross.

What actually happened when House Democrats called Bolton to testify

In the fall of 2019, House impeachment investigators were already talking to several current and former top staffers on Bolton’s national security team, one of whom testified that Bolton called the Ukraine scheme “a drug deal” and said he wanted no part in it.

In November, Democrats asked Bolton to testify voluntarily and set a date. Even top Republicans said they wanted to hear from Bolton. He didn’t show. Then his lawyer sent a letter to House Democrats saying that Bolton would sue them if they tried to subpoena him.

Ignoring a congressional subpoena is normally a crime that can be punishable by a fine or jail time. But Bolton’s former No. 2 at the National Security Council had just been subpoenaed and told by the White House not to comply (even though he didn’t work there anymore). So Charles Kupperman filed a lawsuit, asking a federal judge which branch of government has the upper hand on whether he should testify: the executive branch or the legislative.

Democrats said Kupperman was trying to drag out a difficult decision well past the impeachment inquiry (since the courts tend to move more slowly than Congress). Kupperman denied that.

Whatever the intention, going to the courts rather than complying with a subpoena from Congress was a move that Bolton decided to follow. His lawyer never filed that lawsuit against House Democrats, but he indicated that Bolton would follow whatever came of Kupperman’s case.

Around the same time, Democrats were trying to talk to then-acting White House chief of staff Mick Mulvaney. He indicated he would join Kupperman’s lawsuit, too.

Democrats argued that the court fight to get all these high-level witnesses would be a waste of time. They said they needed to move forward with Trump’s impeachment now, because it dealt with foreign interference in the presidential election, and another election was less than a year away.

They withdrew the subpoena for Kupperman and never subpoenaed Bolton. And they spent a significant amount of time and energy defending that decision.

“'Why don’t you let him cheat in one more election?'" House Intelligence Committee Chairman Adam B. Schiff (D-N.Y.) said at the time of Republicans who argued that Democrats should wait for the lawsuits to play out before moving on with impeachment. “That is what that argument amounts to.”

Democrats impeached Trump without Bolton’s testimony on Dec. 18. The Kupperman case still had not received a ruling from a judge. On Dec. 30, a federal judge tossed out the lawsuit on whether Bolton’s top aide should testify, calling it moot. But the potential for Bolton’s testimony would continue to shadow the impeachment process.

What happened when the Republican-controlled Senate started its impeachment trial

The trial in the Senate offered a new opportunity for Democrats to try to get Bolton to testify. But Republicans controlled the votes for that and seemed intent on not letting any witnesses testify, least of all Bolton. Publicly, they argued it was the House’s job to do the investigating, and privately they seemed unwilling to dig into evidence that could be damaging to Trump.

Bolton complicated their public-facing argument by saying in a statement about a week before the trial started that he would be willing to testify if the Senate voted to call him: “Accordingly, since my testimony is once again at issue, I have had to resolve the serious competing issues as best I could, based on careful consideration and study. I have concluded that, if the Senate issues a subpoena for my testimony, I am prepared to testify,” he said.

Bolton could safely assume it was unlikely that Republicans in the Senate would vote to call him. But as the trial got going, the New York Times got an excerpt of Bolton’s book and reported that he tied Trump to holding up Ukraine’s military aid until the government in Kyiv would do him a political favor. (He does indeed write that.)

Democrats ramped up their pressure on Republicans to vote to allow Bolton to testify. “The Senate trial must seek the full truth, and Mr. Bolton has vital information to provide,” House impeachment managers said. Schiff offered Bolton the chance to provide written testimony, which he said Bolton declined to do.

The effort to call witnesses to testify in the Senate fell short by two votes. The trial ended a few days after that, with the Republican-controlled Senate acquitting Trump on the House’s two charges.

What happens next

Bolton now says he doesn’t think his testimony would have made any difference. I’ve argued he’s right: Partisan loyalty being what it is, it’s hard to see how 20 Republicans would have agreed to kick Trump out of office. Plus some Republican senators said at the time that they were convinced Trump did what he was accused of. (They just didn’t think it amounted to impeachment.)

Still, Bolton has put Democrats in another tough position by sharing what he knows too late to be used in their impeachment inquiry.

Now they are forced to consider whether they want to try to call Bolton to the witness table to re-litigate this. And there’s no guarantee Bolton would be any more willing to talk to them.