David Simas, Assistant to the President and Deputy Senior Advisor for Communications and Strategy. July 12, 2013. (Lance Rosenfield/Prime) David Simas, Assistant to the President and Deputy Senior Advisor for Communications and Strategy. July 12, 2013. (Lance Rosenfield/Prime)

Americans will be able to sign up on Oct. 1 for health insurance under Obamacare even if the government shuts down, White House deputy senior adviser for communications and strategy David Simas told reporters Wednesday.

"In terms of outreach, we are good to go," Simas said, speaking at the "Inside Politics with Bill Schneider" breakfast at the think tank Third Way. "On October first we will be up and running and people will be able to shop for a plan."

"There may be some impacts... but it does not go into the core of what we are doing," he added.

Eighty-five percent of the Affordable Care Act's funding comes from mandatory spending that would not be affected by a shutdown, and the Health and Human Services Department has already sent out much of the money that comes from discretionary accounts.

At the same time, Simas downplayed expectations that huge numbers of Americans would sign up for health insurance on the day enrollment begins. He joked that reporters should not focus too much on the single-day results for Oct. 1: "There will not be exits."

"October will be light for enrollment," he said, adding that the numbers would likely rise in November and then again in December since that will be shortly before new plans would take effect.

Registration will likely dip again in January and February before rising in March before the enrollment period ends, Simas said, adding that Massachusetts saw a similar pattern when that state implemented its universal coverage plan.