An additional $1 million came from Morton Bouchard of Melville, N.Y.
Right to Rise USA has plowed nearly $65 million of its haul into television spots, digital ads and mailers aimed at boosting Bush, making it by far the biggest independent spender on the 2016 presidential race. In a distant second is Conservative Solutions PAC, which has shelled out more than $20 million to support Sen. Marco Rubio (Fla.).
In recent weeks, Right to Rise has unleashed a slew of attacks against Rubio and other establishment-friendly GOP presidential candidates, despite criticism among some Republicans that it should aim its firepower at front-runner Donald Trump.
Still, even with the super PAC's substantial air support, Bush has struggled to gain traction. In Iowa, which will hold the first-in-the-nation caucuses Monday, Right to Rise has spent more than $14 million, but the former governor remains mired in the single digits in polls.
The super PAC ended 2015 with $58.6 million in the bank.
Anu Narayanswamy contributed to this report.