Arizona Sen. Jeff Flake has come under intense pressure from voters to break with Republicans and protect Obamacare.

On Monday, Flake revealed where he stands, through a reporter's tweet: He backs a plan that comes closest to shutting down Obamacare.

In a statement to 12 News Wednesday, Flake confirmed that the plan -- Texas Sen. Ted Cruz's "Consumer Freedom Amendment" -- is the most conservative response to repealing Obamacare:

"If you define the most conservative Obamacare repeal plan as the plan that restores Arizonans' freedom to purchase more affordable health insurance of their choosing – rather than the federal government mandating what exactly coverage they must purchase – and still guarantees federally-subsidized coverage for individuals with pre-existing conditions – then yes, I support the most conservative Obamacare repeal plan."

Conservative groups, like Club for Growth, that oppose the existing Republican senate bill, the Better Care Reconciliation Act, are getting behind the Cruz plan. It's the only one, they say, that gives consumers choice and repeals Obamacare.

The Cruz amendment would require insurers to offer one plan that sticks to Obamacare rules. But insurers would also be allowed to sell stingier plans that don't follow the rules, like insuring pre-existing conditions.

On Wednesday, the country's major health insurers came out against the Cruz plan.

They warn that the Obamacare plans might become unsustainable with poorer, sicker Americans. And middle-income Americans with health care needs could be priced out of insurance with the unregulated plans.

There's no Congressional Budget Office analysis of the Cruz amendment because it's not in a bill yet. But it could be inserted in the BCRA.

Senate Republicans are expected to release their latest version of an Obamacare repeal bill Thursday.

Flake said his support for the Cruz amendment doesn't indicate how he will vote on the BRCA.

"My decision will be based on how it balances two principles. The first is that the legislation needs to ensure that those who currently have coverage do not have the rug pulled out from under them. The second is that the Senate must agree on a solution that is fiscally sustainable."