Two top aides to Republican presidential candidate Ben Carson have quit the campaign, NBC News has confirmed.
In another sign that Carson's campaign is struggling, Campaign Manager Barry Bennett and Communications Director Doug Watts have resigned amid the one-time top-tier candidate's dropping poll numbers.
"Barry Bennett and I have resigned from the Carson campaign effective immediately," Watts said in a statement. "We respect the candidate and we have enjoyed helping him go from far back in the field to top tier status. Having just announced raising $23m(illion) for the 4th Q(uarter), more than any other Republican candidate, and passing 1 million contributions and and over 600 mm unique donors since March, we are proud of our efforts for Dr Carson and we wish him and his campaign the best of luck."