has been impugning

• present perfect progressive

  present perfect progressive

  Used to describe an action that began in the past, has continued continuously, and is still in progress.

  of impugn (3rd person singular).
  impugn

  verb (used with object)

  to challenge as false (another's statements, motives, etc.); cast doubt upon.

Related Words

• assail
• contravene
• tar