As crisis has engulfed Boeing following the near-catastrophic accident on an airborne 737 Max 9 aircraft in January, Chief Executive Officer Dave Calhoun has kept an increasingly low profile.

Now he faces a very public grilling from U.S. senators accusing Boeing of putting profit before safety. A hearing on Tuesday will put Calhoun on the spot to defend his record and salvage his legacy as he prepares to step down later this year.

Investors who have endured a 32% stock slump this year and watched Boeing’s credit rating come dangerously close to junk status have already shifted their focus to Calhoun’s yet-undisclosed successor. Boeing's new chairman, Steve Mollenkopf, who took over as part of a senior management shakeup in March, is leading the search for the next CEO — and the hunt has picked up speed in recent weeks, say people close to the matter.