Michael Bloomberg has claimed California Sen. Kamala Harris' plan to abolish private health insurance in favor of 'Medicare for all' would bankrupt the country.

The former New York City mayor - who is considering running for the Democratic presidential nomination - rejected the idea endorsed by his 2020 rival, which is gaining traction in the party.

'I think you could never afford that. You’re talking about trillions of dollars,' Mr Bloomberg said during a political swing in New Hampshire, where the nation’s first primary will be held next year.

Michael Bloomberg (pictured at a political swing in New Hampshire yesterday) has claimed abolishing private health insurance in favor of 'Medicare for all' would bankrupt the country

The former New York City mayor - who's considering running for the 2020 presidential election - said the move would cost trillions of dollars. He proposed providing it only to those currently uninsured

'I think you can have "Medicare for all" for people that are uncovered, but to replace the entire private system where companies provide health care for their employees would bankrupt us for a very long time.'

While Bloomberg is considering running on a centrist position, Harris carved out a liberal platform on Monday night, telling an audience of Iowa Democrats that the United States should 'eliminate' all private plans and move everyone to a single-payer system.

'We need to have Medicare for all. That's just the bottom line,' Harris said during a CNN town hall event, declaring that she feels 'very strongly' about it.

'The idea is that everyone gets access to medical care, and you don't have to go through the process of going through an insurance company, having them give you approval, going through the paperwork, all of the delay that may require,' she explained, concluding that private insurers should not be part of the system.

Senator Kamala Harris of California made her first town hall appearance as a Democratic presidential candidate on Monday, saying she wants to abolish private health insurance

Harris spoke with reporters at Drake University on Monday night after the town hall event, hosted by CNN's Jake Tapper

'Let's eliminate all of that. Let's move on,' said Harris.

Republicans were quick to mock what they typically call socialized medicine, something that has become more mainstream in the Democratic party since the early part of the 2016 presidential campaign cycle.

GOP spokesman Michael Ahrens tweeted a dig at Harris that also doubled as a jab at former president Barack Obama's frequent promises about his namesake health law.

'Dems in 2009: If you like your plan, you can keep it,' Ahrens mocked. 'Dems in 2019: If you like your plan, we're eliminating it.'

Harris is advocating a 'Medicare for all' platform that would put government agencies in charge of health coverage; that's an approach that goes further than the Obamacare system, and had Bernie Sanders as its main advocate in 2016

Harris also defended other positions she took as California's attorney general that are unpopular with some Democrats, saying at the Drake University event in Des Moines that they reflected her duty as the state's top law enforcement officer.

CNN anchor Jake Tapper asked her about prosecuting death penalty cases, and about legislation requiring her office to investigate all fatal police-related shootings.

Harris, who was attorney general from 2011 until she became a U.S. senator in 2017, said she enforced the death penalty despite opposing it.