John Bolton was a no-show on Capitol Hill Thursday. He was scheduled for a voluntary interview with the Congressional committees conducting the impeachment inquiry.

There were earlier reports that Donald Trump’s former national security adviser would cooperate if he was subpoenaed, but that seems to be off the table. His attorney now says Bolton would only testify if a federal court cleared the way, a process that could take months.

CNN legal analyst Renato Mariotti, a former federal prosecutor remarked:

This is a clear delay tactic by Bolton. The White House could not prevent him from testifying, so this is just an excuse not to appear.

This comes as disappointing news to those who believed Bolton would potentially become the highest-ranking former member of the Trump administration to testify. The Washington Post reports:

Bolton could be a powerful witness for Democrats: Top State Department and national security officials have already testified that he was deeply concerned about efforts by Trump and his allies to push Ukraine to open investigations into the president’s political rivals while the Trump administration held up military aid to that country.

The former national security adviser, who abruptly left his post in September, is expected to confirm their statements and describe his conversations with Trump, according to the people, who spoke on the condition of anonymity because of the ongoing inquiry.