He says his political enemies have been conducting a 'stealth' [='secret'] campaign to block his nomination.
The fox uses 'stealth' and cunning to hunt its prey.
a 'stealth' bomber/fighter
(..) Now! Hey big guy. We did it. The job's finished. Now I need you to turn this bird around, okay? We can't track you in stealth mode, so help me out. I need you t... Oh, dear. You're afraid. - Of you? - Of death. (..)2015 Avengers: Age of Ultron
(..) Stark Relief Foundation? Already on the scene. - How's the team? - Everyone's...we took a hit. - We'll shake it off. - Well for now I'd stay in stealth mode. And stay away from here. So, run and hide? Until we can find Ultron, I don't have a lot else to offer. Neither do we. (..)2015 Avengers: Age of Ultron