WASHINGTON — The principal contractors responsible for the federal government’s trouble-plagued health insurance website say the Obama administration shares responsibility for the snags that have crippled the system.

Executives of CGI Federal, which built the federal HealthCare.gov website serving 36 states, and QSSI, which designed the part that verifies applicants’ income and other personal details, are testifying today before the House Energy and Commerce Committee.

The hearing comes as President Barack Obama’s allies are starting to fret about the political fallout. Democrats had hoped to run for re-election next year on the benefits of the health care law for millions of uninsured Americans. Instead, computer problems are keeping many consumers from signing up through new online markets.

One House Democrat says the president needs to “man up” and fire somebody, while others are calling for sign-up deadlines to be extended and a reconsideration of the penalties individuals will face next year if they remain uninsured.

On that point, a change in the timeline for signing up for coverage is under way, the White House said. Consumers have until Dec. 15 to apply for coverage that’s effective Jan. 1. Even though open enrollment lasts until March 31, people would face a penalty if they postpone buying coverage beyond mid-February. Calling that a “disconnect,” the White House said officials will soon issue policy guidance allowing consumers to sign up by the end of March without penalty.

The focus on the contractors is a first step for GOP investigators. After the failure of their drive to defund “ObamaCare” by shutting down the government, they’ve been suddenly handed a new line of attack by the administration itself. Administration officials, including Health and Human Services Secretary Kathleen Sebelius, are to testify next week.

Cheryl Campbell, senior vice president of CGI, suggested in prepared testimony that Congress should look beyond the contractors.

Andy Slavitt, representing QSSI’s parent company, blamed the administration, saying that a late decision to require consumers to create accounts before they could browse health plans contributed to the overload. “This may have driven higher simultaneous usage of the registration system that wouldn’t have occurred if consumers could window-shop anonymously,” he said.

Rep. Joe Pitts, R-Pa., chairman of the panel’s health subcommittee, said he wants to focus on the administration’s decision not to allow browsing, or window-shopping. That’s a standard feature of e-commerce sites, including Medicare.gov for seniors.