A persistent buzz about Secretary of State Mike Pompeo stepping down to run for an open Senate seat in Kansas has built to a roar.

It’s happening as impeachment hearings into President Donald Trump have intensified scrutiny of the State Department.

The top U.S. diplomat was in Brussels on Wednesday. He brushed off questions about the impeachment inquiry and dismissed speculation about how long he’ll stay in Trump’s administration.

His trip came while lawmakers heard testimony from Ambassador Gordon Sondland that he kept Pompeo informed of efforts to pressure Ukraine into investigating former Vice President Joe Biden.

Strain has set in between Trump and Pompeo.

And Republicans already have speculated for months that Pompeo will resign to run for the Senate in his home state.