House Democrats have reportedly weighed drafting three articles of impeachment against President Donald Trump, sparked by a so-called “whistleblower’s” mischaracterization of the president’s phone call with the leader of Ukraine.

According to ABC News, Democrats are evaluating articles charging President Trump with abuse of power, obstruction of justice, and contempt of Congress.

Impeachment investigators believe the president could be charged with abuse of power for floating to Ukrainian President Volodymyr Zelensky to look into allegations of corruption against former Vice President and 2020 White House contender Joe Biden, along with his beleaguered son, Hunter Biden. Further, lawmakers believe the president may have obstructed justice and be in contempt of Congress for defying subpoenas for documents and witness testimony.

“They have also weighed an obstruction of justice charge centered on the president’s efforts to obstruct former special counsel Robert Mueller’s investigation,” ABC News reports.

The development comes as former national security adviser John Bolton opted against interviewing with congressional investigators on Thursday.

An attorney for Bolton, Charles Cooper, said his client had not received a subpoena. Cooper had previously said Bolton would not appear without one.

A House Intelligence committee official said the panel has no interest in engaging in a drawn-out court fight over a subpoena for Bolton and will simply add the White House’s instructions against testifying as evidence of the president’s obstruction of Congress.

Even as Bolton was a no-show, an aide to Vice President Mike Pence came to the Capitol to speak with impeachment investigators. Jennifer Williams, a career foreign service officer detailed to Pence’s office from the State Department, was subpoenaed to appear.

Speaking to reporters in New Hampshire, Pence stood by President Trump and said if Americans read the administration’s rough transcript of the call they will find “there was no quid pro quo, the president did nothing wrong.”

Pence called the impeachment inquiry a “disgrace.”

Investigators are wrapping up the private interviews as they prepare to start public hearings next week. House Intelligence Committee Chairman Adam Schiff (D-CA) announced Wednesday that three State Department witnesses will appear in two hearings next Wednesday and Friday: top Ukraine diplomat William Taylor, career department official George Kent, and Marie Yovanovitch, the former U.S. ambassador to Ukraine.

The Associated Press contributed to this report.