A key ObamaCare official engaged in a “cruel and uncaring march” to launch the federal health care website last year and wasn’t open to seeking a delay despite concerns, according to a newly revealed email from her former second-in-command.

The damning email from Michelle Snyder, the then-chief technology officer at the Centers for Medicare and Medicaid Services, was released to FoxNews.com ahead of a Wednesday House Science, Space and Technology subcommittee hearing on the security and botched rollout of Healthcare.gov.

In the September 2013 email to Todd Park, the former Chief Technology Officer of the U.S., Snyder characterized her then-boss, CMS Administrator Marilyn Tavenner, as a temper tantrum-throwing, demanding official who vowed the website would launch on time "no matter what."

Snyder implied that Tavenner had threatened her job if Snyder was unable to deliver.

“Just so you know (Tavenner) decided in January we were going no matter what,” Snyder wrote. “Hence the really cruel and uncaring march that has occurred since January when she threatened me with a demotion or forced retirement if I didn’t take this on.”

Snyder’s words may have been prophetic --- she announced her retirement just a few months later. She told Park that Tavenner did not have a good enough understanding of the risks of launching before the website was ready to fight for a delay.

“Do you really think (Tavenner) has enough understanding of the risks to fight for a delay --- no and hell no,” she wrote.

She later added: “I appreciate you (sic) belief in the goodness of others but at this point I am too tired to pretend that there is a decision to be made - it is just how much crap my team will have to take if it isn’t sufficiently successful – you haven’t lived through the temper tantrums and threats of the last 9 months.”

Snyder was in charge of the rocky rollout and announced her retirement last December in the midst of the turmoil. Tavenner said at the time that Snyder had actually planned to retire the previous year, but had stayed on in order to help "with the challenges facing CMS in 2013."

The CMS did not respond to an emailed request for comment from FoxNews.com.

The House Science, Space and Technology Committee obtained the email and others through a subpoena to compel Park to testify on how much knowledge he had about security concerns with the website before it launched in October 2013.

The committee is investigating how much Park and the White House knew about the problems with the website before the launch.

Park has distanced himself from the website’s problems, telling a House committee last year that he did not “actually have a really detailed knowledge” of the website before the launch and was “not even familiar with the development and testing regimen that happened prior to October 1.”

However, the emails from Park, who briefed the White House on the progress of the website, seem to indicate he had more knowledge of the website than his statements indicate. In the emails, he mentions specific teams, hardware and user targets for the website.

The Wednesday hearing comes after the beginning of the second round of open enrollment for the health care law. The enrollment period began Saturday with few issues compared to the previous period, which was plagued with site outages and other problems.

Committee chairman Rep. Lamar Smith told FoxNews.com in a statement the hearing is especially important because Americans are in the process of signing up for ObamaCare.

"It’s time for the White House to come clean with the American people about the security of the Obamacare website," Smith, R-Texas, said.