They’ll also want to know what, if anything, Secretary of State Mike Pompeo did to rein in Giuliani and other outside actors — as well as Trump — as they sought to pressure Ukraine’s government to investigate former vice president Joe Biden, a Trump political rival.

The hearing also offers an opportunity for Senate Democrats to question the administration’s overall Russia policy, which critics say has been warped by Trump’s unusual affinity for Russian President Vladimir Putin.

Earlier this month, the Democrats on the Senate committee wrote to its Republican chairman, James Risch of Idaho, asking him to convene hearings on the Trump-Ukraine issue.

“The Foreign Relations Committee has an obligation to examine the serious questions raised by these events,” the senators stated in the Oct. 9 letter, which was led by the committee’s ranking Democrat, Robert Menendez of New Jersey.

In a response dated Tuesday, Risch said he preferred to wait on holding hearings until after the House had finished its impeachment inquiry “one way or another.“

“It is important that the Senate reserve its judgment on these matters until the House formally completes its work on this inquiry,” Risch wrote. “There are vital U.S. national interests at play here, and I hope the strong bipartisan support for Ukraine is not compromised.“

That stance means Sullivan’s nomination hearing is an opening Democrats can’t ignore.

As the No. 2 official at the State Department, Sullivan has a broad purview and is frequently copied on communications involving Pompeo.

It was Sullivan who broke the news to Yovanovitch that she was being yanked out of Kyiv early, according to Yovanovitch’s testimony to impeachment investigators. Yovanovitch said Sullivan told her that Trump wanted her gone, even though she had “done nothing wrong.”

It’s unclear how much Sullivan will be willing to say on anything impeachment-related during his hearing; he may just defer to legal advisers given the political perils involved.

Asked for comment, a State Department official said Sullivan “looks forward“ to the hearing. “We hope for an expeditious confirmation so John Sullivan can quickly assume his duties and join the dedicated men and women on the frontlines of American diplomacy at Embassy Moscow,“ the official added.

Generally speaking, lawmakers from both parties hold Sullivan in good regard, and his nomination to serve as the U.S. ambassador in Moscow is likely to be approved in the coming weeks. He will succeed Jon Huntsman, the former Utah governor.

Risch has wanted to hold hearings related to U.S.-Russia policy, and that could still happen. A Republican committee aide said the State Department has said it is willing to send another top Pompeo aide, David Hale, to appear for a Russia-related session.

Hale, the undersecretary of state for political affairs, is a career Foreign Service officer whose role in the Ukraine issue remains unclear. But given his top position, a hearing ostensibly about Russia policy is almost certain to touch on impeachment, too.

At his hearing Wednesday, Sullivan is likely to also face some questions about alleged political retaliation against career staffers at the State Department, Senate Democratic aides said.

While Yovanovitch has become a prominent example of such alleged retaliation, her case is relatively new. Foreign and civil service employees at State have accused Trump political appointees of mistreating them dating back to the early days of the administration.

Some believe Sullivan, himself a political appointee, hasn’t done enough to protect career staffers, nor enough to punish perpetrators. But there’s a recognition that Sullivan can only do so much, and he remains a more popular figure within the department than Pompeo.