WASHINGTON – Michigan Gov. Rick Snyder is responsible for lead contamination in Flint, Michigan's water supply and would likely face criminal charges if he were running a business, a Democratic lawmaker said Thursday.

"There is no doubt in my mind that if a corporate CEO did what Governor Snyder's administration has done, he would be hauled up on criminal charges," Rep. Elijah Cummings of Maryland, the senior Democrat on the House Oversight and Government Reform Committee, said of the Republican governor.

"The board of directors would throw him out. And the shareholders would revolt," Cummings said.

Snyder told the panel at a contentious hearing that the Michigan Department of Environmental Quality repeatedly gave him assurances that water being piped in from the Flint River was safe, when in reality it had dangerous levels of lead.

Complete Coverage: Flint Water Crisis

But Cummings said the governor should have done more to push back against state experts. The committee has obtained documents "showing that people all around the governor were sounding the alarms, but he either ignored them or didn't hear them," Cummings said, citing emails showing that Snyder's top legal adviser warned in October 2014 that Flint should "get back on the Detroit (water) system" as soon as possible "before this thing gets too far out of control."

Watch: Rep. Cartwright tells Gov. Snyder to resign over Flint water crisis

The warning came a year before Snyder says he became aware of the lead contamination on Oct. 1, 2015.

"The governor's fingerprints are all over this" crisis, Cummings said. "His Department of Environmental Quality. His Department of Health and Human Services. His inner circle of top aides. His press staff. And of course the emergency managers the governor put in charge of Flint."

Snyder said he took immediate action after learning that Flint's water was contaminated nearly 18 months after the city began drawing its water from the Flint River in April 2014 to save money. He reconnected the city with Detroit's water supply, distributed water filters and began testing residents -- especially children -- for elevated lead levels, Snyder said.

"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," Snyder said.

Ultimately, Snyder says, he wonders how he could have prevented the disaster. "That's why I am so committed to delivering permanent, long-term solutions and the clean, safe drinking water that every Michigan citizen deserves," he said.

Rep. Jason Chaffetz, R-Utah, chairman of the oversight panel, said the U.S. Environmental Protection Agency also deserves blame in the Flint crisis.

"You failed," Chaffetz told EPA Administrator Gina McCarthy. "You had authority under the law (to fix problems in Flint) and you didn't do it."

Chaffetz and other Republicans complained that while Snyder has apologized for his role in the Flint crisis, McCarthy and other EPA have repeatedly denied responsibility. Chaffetz said he was especially galled by McCarthy's comment that it was "courageous" for the EPA's Midwest regional chief to resign as the Flint crisis worsened.

Chaffetz called the comment offensive and told McCarthy, "If you want to do the courageous thing, then you, too, should resign."

McCarthy, for her part, faulted state officials for the crisis, which occurred when Flint switched from the Detroit water system and began drawing from the Flint River to save money. The impoverished city was under state management at the time.

"The crisis we're seeing was the result of a state-appointed emergency manager deciding that the city would stop purchasing treated drinking water and instead switch to an untreated source to save money," McCarthy said. "The state of Michigan approved that decision, and did so without requiring corrosion control treatment. Without corrosion control, lead from pipes, fittings and fixtures can leach into the drinking water. These decisions resulted in Flint residents being exposed to dangerously high levels of lead."

Under questioning from Chaffetz, McCarthy said the EPA should have done more to head off the crisis, but she repeatedly said she did not have the authority to "pull a switch" and force Flint to change its water source. The EPA issued an emergency order about Flint's water in January 2016, several months after Flint switch back to the Detroit water system.

Watch: Rep. Carter grills EPA Administrator McCarthy on role of the EPA

Snyder asked to testify to Congress last month, bowing to demands by Democrats that he explain his role in a cost-cutting move that resulted in a public health emergency that has rocked Flint and caused ripples in the presidential campaign, where Democratic candidates have called for Snyder to step down.

A state investigation has "uncovered systemic failures at the Michigan" Department of Environmental Quality, Snyder says. "The fact is, bureaucrats created a culture that valued technical compliance over common sense -- and the result was that lead was leaching into residents' water."

In response to the crisis, the state has approved $67 million in emergency spending, with a request for $165 million more, Snyder said. The governor called for Congress to approve a bipartisan bill that would spend $220 million to fix and replace lead-contaminated pipes in Flint and other cities. Senators from both parties have reached a tentative agreement, but the bill remains on hold amid objections by Sens. Mike Lee, R-Utah, and Bill Nelson, D-Fla.

Watch: Snyder testifies at congressional hearing over Flint water crisis