According to fourth quarter financial figures released by the party, the longtime backroom strategist raked in $156,597 from last October to the end of December.
The first to officially enter the race, Topp also raised $11,850 in September.
Montreal MP Thomas Mulcair was a relatively close second, raising $145,863.
Toronto MP Peggy Nash raised $108,223.
The other five pulled in less than $100,000 each.
Ottawa MP Paul Dewar raised $93,931; British Columbia MP Nathan Cullen pulled in $86,109; Nova Scotia pharmacist Martin Singh, $49,077; Quebec MP Romeo Saganash, $17,552 and Manitoba MP Niki Ashton, $10,215.
Nova Scotia MP Robert Chisholm, who pulled out of the race before Christmas, also raised $35,400.
The NDP has set a $500,000 spending limit for each candidate during the seven-month contest. None of the contenders has come close to raising that amount.
The party will choose a new leader on March 24 to succeed the late Jack Layton, who died of cancer last August.