A challenge for actual bias may be taken for the cause mentioned in RCW 4.44.170(2). But on the trial of such challenge, although it should appear that the juror challenged has formed or expressed an opinion upon what he or she may have heard or read, such opinion shall not of itself be sufficient to sustain the challenge, but the court must be satisfied, from all the circumstances, that the juror cannot disregard such opinion and try the issue impartially.