GAO spokesman Charles Young said just which states will be included with Oregon will be determined as the investigation goes forward. But 14 states and the District of Columbia opted to create their own exchanges and accepted federal funding to do so.
Republicans have been stepping up their attacks on troubled health exchanges during this election year, but Rep. Greg. Walden, R-Ore., said it was a non-partisan issue.
He noted Oregon Democratic Sens. Ron Wyden and Jeff Merkley made their own requests for the GAO to investigate a day after the Republicans — Walden, House Committee on Energy and Commerce Chairman Fred Upton of Michigan, and Reps. Joe Pitts and Tim Murphy of Pennsylvania — filed theirs last month.
"The politics will play out where they may, good or bad," Walden said. "That doesn't mean you don't ask questions. We need to get answers."
Merkley said in a statement that he looked forward to the GAO's recommendations "about how to fix the system and avoid this happening in the future."
Cover Oregon spokesman Michael Cox said, "We will participate fully with the GAO as they conduct their work."
Walden added that the probe of state websites would "piggyback nicely" on another GAO look at the federal health exchange website, which has already begun.
Separately, HHS Secretary Kathleen Sebelius has asked for an inspector general's investigation into problems with the rollout of the healthcare law.
Some of the state exchanges have outperformed the federal exchange website, but others have trailed behind and faced significant challenges, including expensive fixes to glitches and lower projected enrollments.
In addition to Oregon, where residents on their own still can't sign up for coverage in one sitting, the exchanges in Maryland, Hawaii, Massachusetts and Minnesota have faced major problems.
Sen. Brian Schatz, D-Hawaii, called the investigation a political stunt.
"With House Republicans voting today for the 50th time to repeal the Affordable Care Act, it is disappointing but not surprising that Republicans are now using federal government resources to investigate state health exchanges instead of finding a productive way to help Americans access healthcare," Schatz said in an emailed comment.
States with successful exchanges include Connecticut, Rhode Island, Kentucky and New York. Connecticut, which has far exceeded its enrollment goals for the open enrollment period, is setting up a consulting business and marketing an "exchange in a box" to other states.
Cover Oregon's online enrollment system was supposed to launch in October, allowing individuals and small businesses to compare insurance plans and qualify for federal tax credits to subsidize the premiums. It wasn't ready, however, forcing people to fill out a lengthy paper application that would have to be processed by hand. Pieces of the website are now working and some portions of the processing are automated, but significant problems still exist.
Republicans have contended problems were known for months before the launch. Gov. John Kitzhaber, a Democrat, has acknowledged mistakes were made but denies having prior knowledge of problems that kept the website from launching on time.
Other questions raised by the Republican request, crafted in consultation with the GAO, include:
What capability does the federal government have to reclaim those funds if Oregon abandons the state-run exchange and joins the federal one?
What other costs has Oregon incurred because of the website's failure?
Did Cover Oregon's status as a state organization play a role in its failure?
What steps could federal agencies have taken to assure state and federal oversight of projects like this in the future?
The Wyden-Merkley request asks more questions:
How were the federal funds used, including job creation, public and private contractors, software developers, and consumer education?
What efforts to enroll people outside the website have been successful, and what can be done to expand enrollment ahead of the March 31 deadline?
If taxpayer funds were mismanaged, can the federal government reclaim grant funds from contractors?
Was there anything in the Affordable Care Act that Cover Oregon did not respond to in its creation?