After former Trump National Security Advisor John Bolton on Monday said he would testify during the Senate impeachment trial if subpoenaed by lawmakers, progressives as well as top Democrats said the ball is now back in Senate Majority Leader Mitch McConnell\u0026#039;s court about whether he will call witnesses and hold a fair trial or forever go down in history as the man who prevented transparency and accountability for President Donald Trump\u0026#039;s alleged abuse of power and obstruction of Congress.\u0022Given that Mr. Bolton\u0026#039;s lawyers have stated he has new relevant information to share, if any Senate Republican opposes issuing subpoenas to the four witnesses and documents we have requested they would make absolutely clear they are participating in a cover up.\u0022 —Senate Minority Leader Chuck SchumerIn a statement, Bolton explained that with legal questions seemingly exhausted by the courts, and with the trial in the Senate looming, he would submit to a subpoena if one is issued.\u0022The House has concluded its Constitutional responsibility by adopting Articles of Impeachment related to the Ukraine matter. It now falls to the Senate to fulfill its Constitutional obligation to try impeachments, and it does not appear possible that a final judicial resolution of the still-unanswered Constitutional questions can be obtained before the Senate acts,\u0022 Bolton said.\u0022I have had to resolve the serious competing issues as best I could, based on careful consideration and study,\u0022 he added. \u0022I have concluded that, if the Senate issues a subpoena for my testimony, I am prepared to testify.\u0022As Josh Marshall of Talking Points Memo noted, Bolton\u0026#039;s remarks felt a bit hollow given that a subpoena issued by the Senate would give him no choice but to testify:Curious what others say. But Bolton\u0026#039;s comment strikes me as meaningless. If he\u0026#039;s subpoenaed in the Senate trial, of course he has to testify. I don\u0026#039;t believe such a subpoena would even be reviewable by a court.— Josh Marshall (@joshtpm) January 6, 2020In response to the news, the progressive advocacy group Stand Up America said it was now up to McConnell and his Republican allies in the Senate to step forward to allow Bolton, and other firsthand witnesses to key events, to take the stand.\u0022The Senate has a constitutional obligation to hold a fair impeachment trial—but Moscow Mitch and Trump\u0026#039;s defenders in the Senate are blatantly rigging the process to cover-up Trump\u0026#039;s crimes,\u0022 said Sean Eldridge, founder and president of Stand Up America, in a statement.Bolton\u0026#039;s willingness to testify, continued Eldridge, should put new pressure on McConnell to work with Democrats in order to create the fair and transparent process that the Senate Majority Leader has so far refused to offer.\u0022McConnell and his Republican colleagues are the only ones standing in the way of the American people hearing what John Bolton has to say. Will they hold a fair trial that airs the evidence against Trump, or will they enable Trump\u0026#039;s cover-up?\u0022 said Eldridge. \u0022History is watching what they do next.\u0022In addition to Bolton, Democrats have expressed desire for White House acting chief of staff Mick Mulvaney, Secretary of State Mike Pompeo, and White House aide Robert B. Blair to testify before the Senate—none of whom were called during the House impeachment hearings.According to The Hill:[Bolton] witnessed key moments leading up to and following the July 25 call during which Trump asked Ukrainian President Volodymyr Zelensky to investigate a debunked theory about Kyiv’s involvement in the 2016 Democratic National Committee server hack as well as former Vice President Joe Biden and his son Hunter Biden’s business dealings in Ukraine.Bolton allegedly described efforts by administration officials to press Ukraine for the investigations as a “drug deal,” according to witness testimony.It\u0026nbsp;would take 51 senators to call Bolton to testify as part of the impeachment trial. All 47 Democrats are expected to back subpoenaing him, meaning they\u0026#039;ll need to win over four Republicans.Democratic Minority Leader Chuck Schumer said the announcement by Bolton means that McConnell should have no choice but to allow witnesses at the trial.\u0022Given that Mr. Bolton\u0026#039;s lawyers have stated he has new relevant information to share, if any Senate Republican opposes issuing subpoenas to the four witnesses and documents we have requested they would make absolutely clear they are participating in a cover-up,\u0022 Schumer said.Vox detailed some of the context and what the new development might mean going forward:The prospect that Bolton might testify is tantalizing for Democrats. He ran the National Security Council during the key period in which Trump blocked military aid for Ukraine and pressured the country to investigate the Bidens. And while Bolton is a staunch conservative, he was alarmed by Trump’s actions, urging NSC aide Fiona Hill to make clear she was \u0022not part of whatever drug deal [Gordon] Sondland and [Mick] Mulvaney are cooking up,\u0022 and calling Rudy Giuliani \u0022a hand grenade,\u0022 according to Hill’s testimony.Yet while the House pursued its impeachment inquiry last year, Bolton was cagey on whether he\u0026#039;d talk. And he eventually suggested he’d fight any subpoena for his testimony in court (perhaps not wanting to stick his neck out too far to help what he saw as a partisan impeachment effort). House Democrats decided they didn\u0026#039;t want to pursue a lengthy legal battle over this, so they ended up choosing not to subpoena him.This, then, is a major change in Bolton’s position. The catch, though, is that it\u0026#039;s not clear whether the Republican-controlled Senate will subpoena Bolton — or any witnesses at all for the impeachment trial.With McConnell holding most of the cards in the Senate, former federal prosecutor and legal analyst Renato Mariotti suggested House Democrats \u0022should issue a subpoena for Bolton\u0026#039;s testimony\u0022 as a way to hear what he has to say.\u0022It\u0026#039;s hard to see any principled reason to comply with a Senate subpoena but refuse to comply with a House subpoena,\u0022 Mariotti explained.