Obamacare's "other" big program is more than keeping pace with its better-known sibling. The Medicaid and CHIP health-care programs that cover the poor and children now have 10.1 million extra people covered since the period just before Obamacare insurance marketplaces launched in the fall of 2013, federal officials said Monday. That's a 17.5 percent jump in the Medicaid/CHIP rolls since the summer of 2013, according to the Health and Human Services Department. The most significant enrollment increases came in states that have loosened eligibility requirements for Medicaid, as allowed by the Affordable Care Act. Medicaid expansion to cover nearly all poor adults is a key pillar of the ACA, along with the creation of government-run exchanges selling private Obamacare insurance plans. Read MoreYou can sell your poop for $13,000 a year: Report

Officials said 444,324 people were added in November 2014 to the Medicaid/Children's Health Insurance Program rolls. As of November, there was a total of 68.97 million people on Medicaid and CHIP, which are jointly funded by the federal government and individual states.

Despite suffering from a past heart attack and diabetes, Kentucky resident Mary Blair was able to receive medical coverage through Medicaid expansion under the Affordable Care Act. Luke Sharrett | The Washington Post | Getty Images

In the 26 states and the District of Columbia that had expanded Medicaid eligibility as of November, there was a nearly 25.5 percent increase in the number of people covered by Medicaid or CHIP since the summer of 2013, officials said.

In the remaining nonexpansion states, enrollment in those programs grew by only about 7 percent over the same period, according to Centers for Medicare and Medicaid Services. Read MoreObama seeks $215 million for 'precision medicine'

Since then, two other states, Pennsylvania and Indiana, have adopted Medicaid expansion. Indiana's expansion program, which could cover up to 350,000 extra people, was approved just last week, and is starting to enroll people this month. Pennsylvania's program started sign-ups in January, and could end up covering as many as 600,000 newly eligible people. Medicaid's added enrollment tally compares favorably with sign-ups in private insurance plans sold on government-run Obamacare exchanges. So far this open enrollment season, about 9.5 million people have selected plans that take effect in 2015 from those exchanges. Unlike Obamacare plans, Medicaid has open enrollment year-round. While some of the new Medicaid beneficiaries in expansion states are newly eligible, the ACA has been credited with boosting enrollment by previously eligible people in Medicaid. The law requires nearly all Americans to have had some form of health coverage as of 2014 or pay a fine, and there was significant publicity about the government-run Obamacare private insurance exchanges from 2013 into 2014.