"We will conclude 2015 with having raised over $45 million," wrote Roe in the memo.
That means the campaign raised nearly $20 million dollars in the fourth quarter of the year, up from the $12.2 million raised in the third quarter.
According to Roe's memo, the campaign had over 670,000 donations from over 300,000 donors in 2015. Some of those donors are what the campaign calls "sustainers" who are giving recurring payments on a monthly basis. Roe wrote that those recurring donations can fund the entire campaign's field operation.
"Some campaigns are focused solely on a man, some on a movement. Ours is a hybrid of the two built to win. We have brought together, and continue to build, a grassroots army of courageous conservatives committed to electing Ted Cruz to reignite the promise of America. Just over a month away from the start of the caucuses and primaries we have a network in place with the resources required to win that is the envy of every other campaign," Roe writes in the memo.
"We finished the last fundraising quarter with more money in the bank than any Republican in the field. That's part of why the Washington establishment is panicking because they are used to having conservatives with no money, no ability to communicate where they can just swap them with false attack ads," said Cruz at a press conference in Las Vegas, Nev. Dec. 17.
Carson’s campaign manager told ABC News that they expect to raise $23 million this quarter, but are still waiting for final numbers.
ABC News' Katherine Faulders contributed to this report.