Enrollment for 2018 doubles compared to last year.
On the first day available to sign up Nov. 1 for coverage in 2018, more than 200,000 consumers enrolled, compared to 100,000 last year, according to the Hill.
The political news website said more than 1 million people visited healthcare.gov on the same day, compared to about 750,000 last year.
It is unclear, however, what the final count of sign-ups will be based on those figures because existing users often renew coverage early in the enrollment season.
Trump has long desired to repeal former President Barack Obama's health care overhaul and fulfill a key campaign promise he said would boost the economy by allegedly lowering tax rates for businesses and middle-class Americans.
Overall enrollment in Obamacare could fall by as much as 1.6 million below last year’s level of 12.2 million signups, in part, due to uncertainty from the administration's actions, according to a forecast last week by Standard & Poor’s financial services.
Last month, Trump signed an executive order halting federal subsidies to insurance companies meant to ease costs for low-income Americans.
The move was Trump's largest blow to Obamacare, and cast the program's future into doubt.
According to the White House, the order also eases the sale of short-term insurance policies the Obama administration restricted.
It will also allows employers to deposit money into special accounts employees can use to purchase their own insurance plans.