Republican presidential hopeful Sen. Ted Cruz raised almost $20 million in the last three months of 2015, a significant improvement over his third quarter fundraising haul.

Cruz's fundraising totals have grown every quarter, which, combined with his steadily rising poll numbers, is a sign of an emerging front-runner, reported The Wall Street Journal.

"We will conclude 2015 with having raised over $45 million," Cruz campaign manager Jeff Roe wrote in a memo to campaign staff

Cruz raised $4.3 million in the first quarter, $10 million in the second and $12.2 million in the third, Roe said, noting that Cruz received more than 670,000 donations from 300,000 supporters, with an average donation of $67.

"Some campaigns are focused solely on a man, some on a movement. Ours is a hybrid of the two built to win," Roe wrote, according to the Washington Examiner. "There's still plenty of work to be done to make Ted the Republican nominee and the next President, but as 2015 comes to a close, we are exactly where we want to be. Go. Fight. Win. This is OUR time!"

Roe said the campaign has a dedicated small-donor base that will be hard for the rest of the GOP field to keep up with, perhaps with the exception of retired neurosurgeon Ben Carson. He also noted that Cruz is the only candidate to receive strong support from both high-dollar and low-dollar donors, according to The Hill.

"Over 10,000 of our donors are 'sustainers' who committed to contribute on an automatic, monthly basis, and provide enough recurring revenue ($500,000 a month) to fund our entire field operation," Roe said.

Roe also said that the Cruz has more than 175,000 volunteers along with coordinators in 163 congressional districts in the 24 states that have nominating contests before March 15, according to the Examiner.

As Cruz's donations surge, so does his position in the polls. A recent CNN/ORC poll showed the Texas senator in second nationally behind real estate mogul Donald Trump, and he is already leading Trump in Iowa, the first caucus state.

Carson also continues to raise money at an impressive rate. His campaign revealed Wednesday night that he brought in $23 million in the fourth quarter, up from $20.8 million in the previous quarter, reported NBC News.