NEW YORK (Reuters) - Consumer sign-ups for Obamacare individual insurance plans were more than 600,000 during the first week of enrollment for 2018, a U.S. health agency said on Thursday, a positive sign for insurers who take part in the healthcare program that Republicans are trying to undo.

A sign on an insurance store advertises Obamacare in San Ysidro, San Diego, California, U.S., October 26, 2017. REUTERS/Mike Blake

The Centers for Medicare & Medicaid Services, a division of the Department of Health and Human Services, said that during the period of Nov. 1 through Nov. 4, 601,462 people, including 137,322 new consumers, selected plans in the 39 states that use the federal website HealthCare.gov.

That represents a daily average of 150,366 sign-ups.

Lori Lodes, a former HHS official who co-founded the enrollment group Get America Covered, said that during the year ago period’s first 12 days, the daily average for sign-ups was 84,018.

The sign-ups were seen as a positive indication of 2018 enrollment despite President Donald Trump’s cut to Obamacare advertising of $90 million and his decision to suspend cost sharing subsidy payments to insurers. Earlier this year, Republican legislators failed to repeal former President Barack Obama’s health reform law, often called Obamacare.

In addition, premiums have risen by an average of 37 percent for 2018, though the income-based premium subsidies the government will pay have also risen, making some plans cheaper than in 2017 for certain customers.

“Perhaps the most important incremental datapoint is that the mix of new enrollees (23 percent) versus renewals (77 percent) is in line with last year,” Evercore ISI analyst Michael Newshal said in a research note. He said that new customers are essential for a stable enrollment period.

Some of the biggest insurers on the exchanges include Anthem Inc, Centene Corp and Molina Healthcare. Both Anthem and Molina cut back their plans for 2018 due to uncertainty about the future of the program, while Centene expanded for next year.

The sign-ups are a good sign for Centene and hospital operators including HCA Healthcare Inc, Newshal said. Centene shares were off $1.18, or 1.3 percent, at $91.96 while HCA was up 20 cents, or 0.3 percent, at $79.06.

Enrollment for HealthCare.gov opened on Nov. 1 and runs through Dec. 15, about half the length of 2017.

About 10 million people are estimated to have such plans right now and another 1 million are seen signing up this year, according to the Congressional Budget Office, a nonpartisan agency.