• Bolton says if he is subpoenaed, he will testify before a Senate impeachment trial
  • Bolton was against the president's decision to withhold military aid to Ukraine  to try to pressure the country into investigating former Vice President Joe Biden
  • Republican leaders in the Senate want to get a trial over with as soon as possible and are against calling witnesses

Update 4:45 p.m. EST

Sen. Josh Hawley, R-Mo., Monday introduced a resolution to dismiss the articles of impeachment before they are transmitted by the House.

"The Constitution gives the Senate sole power to adjudicate articles of impeachment, not the House. If [House] Speaker [Nancy] Pelosi is afraid to try her case, the articles should be dismissed for failure to prosecute and Congress should get back to doing the people’s business," Hawley said in a press release announcing the legislation.

Ten other lawmakers attached their names to the resolution.

Update 3 p.m. EST

Senate Minority Leader Chuck Schumer said now calling former national security adviser John Bolton to testify before President Trump's impeachment trial would amount to a "cover-up."

"Given that Mr. Bolton’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,” Schumer said in a statement.

Original story

Former national security adviser John Bolton said Monday he would testify at a Senate impeachment trial if subpoenaed as President Trump again railed against the process, calling it a “hoax” and waste of time.

Bolton, citing constitutional issues, declined to testify before House impeachment investigators, saying he would appear only if the courts directed him to do so. Trump had directed key administration officials not to cooperate with the House inquiry.

In a statement on his website, Bolton said a House subpoena would have presented him with serious jurisdictional questions, but since the House has concluded its investigation and past subpoenas are moot, “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.”

The House adopted two articles of impeachment against Trump last montgh, accusing him of abusing the power of his office for personal gain and trying to block the House investigation of his actions. The articles have yet to be transmitted to the Senate for trial.

Bolton has said he could shed light on the issues at hand. One of the witnesses who testified before House impeachment investigators said Bolton was frustrated by the efforts of others to get Ukraine to investigate former Vice President Joe Biden. Trump withheld $391 million in military aid to Ukraine to try to pressure the former Soviet republic into announcing an investigation. Bolton was opposed to the action and worked to get the money released.

“I am not part of whatever drug deal [U.S. Ambassador to the European Union Gordon] Sondland and [acting White House Chief of Staff Mick] Mulvaney are cooking up,” former Bolton aide Fiona Hill quoted him as saying.

The White House has asserted “absolute immunity” for all senior advisers to keep them from testifying.

The Republican leadership in the Senate has been resisting calls for witness testimony during an impeachment trial, arguing it’s not the Senate’s role to shore up the case against Trump. Senate Minority Leader Chuck Schumer, D-N.Y., has said lawmakers need to hear from key administration officials with direct knowledge of the events, including Bolton, Mulvaney and Secretary of State Mike Pompeo.

Senate Majority Leader Mitch McConnell, R-Ky., has said the Senate should dispatch with the proceedings as quickly as possible since there’s “no chance” Trump will be convicted. He also said he is working closely with the White House in shaping a trial.

Sen. Lindsey Graham, R-S.C., who chairs the Senate Judiciary Committee, urged the Senate to change its rules on impeachment if House Speaker Nancy Pelosi continues to hold back the articles. Graham, a close Trump ally, said he would work with McConnell to proceed with the trial without having the charges against Trump in hand.

Meanwhile, Trump called the impeachment process a waste of time and energy and a hoax.

He said Pelosi is withholding the articles because they are weak.

He also called the impeachment process a continuation of the investigation by special counsel Robert Mueller into whether the Trump campaign colluded with Russian agents.