WASHINGTON, D.C. -- Gov. Rick Snyder left today's Congressional hearing on the Flint water crisis still facing criticism for his actions, questions about his account of what happened and fresh calls for his resignation.

"Governor Snyder, plausible deniability only works when it's plausible, and I'm not buying that you didn't know about any of this until October 2015," U.S. Rep. Matt Cartwright said during the hearing of the House Committee on Oversight and Government Reform. "You were not in a medically induced coma for a year, and I've had about enough of your false contrition and phony apologies."

Snyder faced the most difficult questioning he has likely experienced since he was elected to his first term as governor in 2011 when he addressed the committee with U.S. Environmental Protection Agency Administrator Gina McCarthy Thursday, March 17.

While the governor faced his toughest examination from Congressional Democrats, McCarthy was also under fire -- particularly from Republicans on the committee -- and both were asked multiple times to resign.

Flint's federally recognized water emergency has landed both officials in the hot seat with members of Congress who are trying to sort out how city was allowed to use the Flint River for drinking water without regulators recognizing the need to treat the water to make it less corrosive.

"Not a day or night goes by that this tragedy doesn't weigh on my mind...the questions I should have asked... the answers I should have demanded... how I could have prevented this," Snyder told Congress. "That's why I am so committed to delivering permanent, long-term solutions and the clean, safe drinking water that every Michigan citizen deserves."

The governor blamed "bureaucrats" in state government for creating "a culture that valued technical compliance over common sense - and the result was that lead was leaching into residents' water."

Snyder has apologized for the state's handling of Flint's water problems -- which started with bacterial contamination, included elevated levels of a cancer-causing byproduct of chlorination and continued with elevated levels of lead.

All of the issues developed while Flint was being run by emergency managers appointed by the governor and while the state Department of Environmental Quality was primarily responsible for ensuring that the city was in compliance with the Safe Drinking Water Act.

Although many key advisers to the governor were aware of problems like rising levels of lead, according to emails and other documents, Snyder has said he didn't realize the severity of the problem of lead poisoning until October 2015 -- about 18 months after the city water source changed.

Rep. Elijah Cummings, D-Md., who joined Cartwright in calling for the governor's resignation today, said he didn't believe Snyder's timeline.

"The governor's fingerprints are all over this," the ranking member of the committee said.

"Governor Snyder has been described as running the state of Michigan like a business ... There is no doubt in my mind that if a corporate CEO did what (his) administration has done, he would be hauled up on criminal charges."

Flint residents who traveled to Washington for today's hearing said in a news conference after the committee meeting that they need more than testimony from state and federal officials.

"We are all damaged. It's obvious after today's hearing that Mr. Snyder cannot ... wrap his mind around that," said Flint resident Keri Webber. "The same goes for (former EPA Regional director Susan) Hedman and ... McCarthy."

"We need a resignation or criminal charge -- I'm open to both," Webber said.

Snyder left the hearing room without responding to questions today but later issued a written statement, saying the water crisis is "a failure of government at all levels."

"Since I first learned that state water experts were wrong about the lead levels in Flint's water, we have been taking action to protect and serve the people of Flint - and all of Michigan - better," the governor's statement says.

"There are thorough, independent investigations underway to identify what went wrong, identify changes we need to make, and help our citizens hold us accountable for fixing this problem."

EPA officials have come under fire for not acting sooner to force Flint into compliance with the SDWA after the state failed to act.

McCarthy said the agency "missed the opportunity late summer to get EPA's concerns on the radar screen.

"That I regret," she said.

Ron Fonger is a reporter for MLive.com. Contact him at rfonger1@mlive.com.