A new study found that 55 percent of American doctors preferred to donate to Democrats over Republicans.

Common belief states that doctors usually favor Republicans during elections. However, the study found that doctors seem to be steering away from Republicans since the mid-1990s.

Researchers at Columbia University looked at doctors' election contributions in 2012 to calculate the difference between the funds that went to Democrats versus Republicans. Outliers were excluded in the computations, such as single donations exceeding $1 million.

The findings showed that the majority of the funds went to Democrats.

Researchers believe that the doctors decided to shift their support to the other party due to the changes in the medical practice, as well as the sudden growth in the number of female doctors who are more supportive of Democrats. Another possibility is that most of the doctors who favor Republicans have either retired or opted not to donate.

"There is this traditional notion out there that if you are a physician, you are a Republican, and we're now seeing that the profession as a whole is on the Democratic side," Dr. David Rothman, senior study author and a researcher at Columbia University's Center on Medicine as a Profession, told Reuters. "We believe it's going to be a long-term trend."

Others agreed that the trend could be long-lasting and that politicians would need to compete harder for the votes of the doctors.

"This trend is going to be pretty lasting, and I think you are going to see a gradual creep in the direction of the Democrats for a while," Theda Skocpol, a professor of government and sociology at Harvard University who wasn't involved in the study, told Reuters.

The study was published in the April 27 issue of the journal JAMA Internal Medicine.