Former National Security Adviser John Bolton has said he is willing to testify at President Trump's Senate impeachment trial, and "Trump's legal defense team and Senate GOP allies are quietly gaming out contingency plans" to make sure that doesn't happen, The Washington Post reports.

Under rules proposed by Senate Majority Leader Mitch McConnell (R-Ky.), the Senate won't vote on whether to allow testimony from new witnesses or other new evidence until after House impeachment managers and Trump's team lay out their arguments and senators ask questions, and four Republicans would have to join all 47 Democrats to approve witnesses. If 51 senators allow subpoenaing witnesses, "McConnell is expected to ensure that those individuals are questioned in a closed-door session rather than a public setting," the Post reports, and Bolton's deposition could be moved to "a classified setting because of national security concerns, ensuring that it is not public."

"But that proposal, discussed among some Senate Republicans in recent days, is seen as a final tool against Bolton becoming an explosive figure in the trial," the Post reports. "First, Republicans involved in the discussions said, would come a fierce battle in the courts," with Trump invoking executive privilege to keep Bolton from talking then asking the courts for an injunction if Bolton "refuses to go along with their instructions."

Republicans are also warning Democrats that if they win on Bolton's testimony, Trump's team will subpoena Hunter Biden — though Senate Democrats seem pretty comfortable with that trade, or perhaps calling that bluff. Nobody's sure if Bolton would help or hurt Trump, but Republicans are not eager to find out. At the same time, a CNN-SSRS poll released Monday found that 59 percent of American adults and a 48 percent plurality of Republicans want the Senate trial to include testimony from witnesses not interviewed by the House. Peter Weber