Updated

A top Democratic senator said Sunday that Secretary of Health and Human Services Kathleen Sebelius will testify before Congress about the problem-plagued ObamaCare website, amid a growing call for her to accept requests to testify.

“Ultimately, Secretary Sebelius will testify,” Sen. Dick Durbin, D-Ill., the chamber’s No. 2 Democrat, told “Fox News Sunday.”

Sebelius and the entire Obama administration has declined requests to testify on Capitol Hill about the site, which has been plagued by crashes, slow responses and other glitches since it went online Oct. 1.

The House Energy and Commerce Committee sent a letter directly to Sebelius last week asking her to testify Thursday on the matter.

Sebelius has yet to respond publicly, but reportedly plans to attend a gala the night before in Boston, which has fueled calls for resignation.

Florida Republican Sen. Marco Rubio said he’s “reluctant” to call for an immediate dismissal in such situations, but was critical of Sebelius for so far not agreeing to testify.

“Her refusal to testify and be transparent has undermined her credibility,” he told Fox News, adding her not testifying could lead to her resignation.

House investigators say they want to know whether officials involved in the website “didn’t know or didn’t disclose” problems, after repeatedly saying the site was “on track” to launch.

Though the White House said this weekend that 476,000 people have applied online for health insurance, officials have yet to say how many people have bought a policy.

Missouri Republican Sen. Roy Blunt told Fox News that Sebelius’ position appears “unsustainable.”

“She cannot sustain it,” he said. “She’ll have to testify.”

Commerce committee Chairman Fred Upton began focusing on Secretary Sebelius after she went to Comedy Central’s “The Daily Show with Jon Stewart” last week to talk about the website.

“Secretary Sebelius had time for Jon Stewart, and we expect her to have time for Congress,” the Michigan Republican has repeatedly said.