The numbers from the Centers for Medicare and Medicaid Services come as Republican senators are pushing to pay for tax cuts by repealing the "Obamacare" requirement to carry coverage.

Millions are expected to forgo coverage if Congress repeals the unpopular requirement that Americans get health insurance, gambling that they won't get sick and boosting premiums for others in a sharp break with the idea that everyone should contribute toward health care.

Uncertainty gripped the Senate on Wednesday over efforts to pass a sweeping $1.5 trillion tax cut after a Wisconsin Republican became the first senator in his party to declare that he could not vote for the tax bill as written, and other senators expressed serious misgivings over the cost and effect on the middle class.

A huge federal cut to health insurance outreach is spurring awareness efforts, with minority and rural communities considered some of the most at risk of missing the message.

The fifth open enrollment period under the Affordable Care Act is off to a strong start in California, with 5,900 people signing up for new health insurance plans on Nov. 1 — 25 percent higher than the first day of open enrollment in 2016, Covered California officials said.

Obamacare is entering its third week of open enrollment and supporters are watching to see if the fast pace of sign-ups will continue.