Sen. Bernie Sanders (I., Vt.) on Sunday was pressed to explain why a single-payer health care system was rejected in Vermont and California, two staunchly Democratic states.

CNN host Jake Tapper said that California and Vermont are "cobalt blue states" and asked how single-payer could be affordable at the national level if they rejected the system at the state level because of the expense.

Sanders pushed back against Tapper, citing "studies that [he] has seen," and said that single-payer would save the average family "significant sums of money."

"If you look at Canada's single-payer health care system per capita, their costs are far far less than the United States," Sanders said. " If you look at the UK, if you look at countries around the world, all of which have different approaches to a national health care system, in every instance, they are spending substantially less per capita than we pay in the United States."

Sanders went on to say the health care system in the United States has not been able to adopt single-payer because it is "so complicated."

"The problem with our system is it is so complicated for the consumer, for the doctors, is that a hospital, for example, might be dealing with 15, 20, 30 different insurance policies," Sanders said. "It takes an enormous amount of time, energy, and expense to figure out that you have a $5,000 deductible, you have a $10,000 deductible."

Sanders said that the single-payer system will save substantial sums of money in administrative costs, lower subscription drug costs, and will do away with the profiteering of drug companies. He added that he would "absolutely" introduce such legislation now that the Republican bill in the Senate to repeal Obamacare has failed.

"Why couldn't this happen in Vermont, then?" Tapper asked. "What's the issue in Vermont? Vermont would be a perfect test case."

"Politically this is difficult," Sanders said. "Look, taking on the insurance companies and the drug companies, taking on Wall Street, taking on a lot of very powerful forces that make millions of dollars a year from the current health care system is not going to be easy."

Single-payer failed to pass in both California and Vermont after lawmakers were unable to figure out how to fund the system. Voters in Colorado also rejected single-payer last year.

Sanders has talked about introducing a single-payer health care bill since March, but has so far not done so. Tapper confronted Sanders earlier this month about breaking his promise to introduce a bill, which he acknowledged and said that he would wait until after the health care vote.

The Obamacare repeal vote failed early Friday morning after Republican Sens. John McCain (Ariz.), Susan Collins (Maine), and Lisa Murkowski (Alaska) voted against it.

According to a report by the Tax Policy Center, Sanders' single-payer proposal during the 2016 presidential election would increase public and private health care spending by $5.5 trillion over 10 years.