Surgeons are much more likely to support Republican candidates than are pediatricians.

PHILADELPHIA — There are red states and blue states, and there are red doctors and blue doctors.

The red doctors are surgeons, and not just because of the blood. They are far more likely to support Republicans than are pediatricians.

In fact, the doctor divide is even redder and bluer than the general public’s, according to an analysis of physician contributions in federal elections: 70 percent of surgeons who made political donations in 2012 gave to Republicans, vs. 22 percent of pediatricians, a gap that exceeds the difference in the presidential vote between red Wyoming (69 percent for Mitt Romney) and blue Vermont (31 percent).

And though the political polarization of specialties has grown over the last two decades, all are trending left, with less than 50 percent of physicians’ donations overall now going to Republicans.

The authors attributed much of the trend to gender and income.

There has been an influx of female doctors, with more going into lower-paying specialties such as pediatrics.

The findings “suggest that the polarization of physician contributions relates to their economic status; physicians in specialties with higher earnings are more likely to contribute to Republicans than those with lower earnings,” the researchers wrote last week in JAMA Internal Medicine.

The pattern went well beyond pediatricians and surgeons; Republican donations tracked almost exactly with incomes of nearly 50 specialties.

Still, money is not the only difference between practice areas.

Pediatricians, infectious-disease, and internal-medicine doctors, all on the low end of the pay scale, may be more likely to see the impact of poverty and unemployment on their patients.

“You are confronted every day with those issues, and realize that you are powerless, that you can’t write prescriptions for food, for jobs, for better housing,” said Gene Bishop, a retired Philadelphia internist.

The high-end specialists “are not asking people about the nitty-gritty of their lives,” said Bishop, who was not involved with the study. “They are (more) procedure-oriented.”