Sen. Bernie Sanders (I-Vt.) called for the resignation of Michigan Gov. Rick Snyder (R) on Saturday for the state's lead in the Flint water supply crisis.

In 2014, the state switched the city's water source to the Flint River to save money and residents began to complain about the quality of tap water. Michigan officials insisted it was safe to drink, even though an internal memo at the Michigan Department of Health and Human Services warned that lead poisoning rates were higher than usual for children under 16. The state continued to say the water was safe until a Flint pediatrician reported in September that there was an unusually high level of lead in Flint children. Lead is an extremely dangerous neurotoxin and can cause children to suffer brain damage.

Bloomberg via Getty Images A spokesman for Rick Snyder said the Michigan governor didn't become aware of the blood lead issue until October.

But Sanders, who is seeking the Democratic nomination for president, said on Saturday that an apology wasn't enough.

“There are no excuses. The governor long ago knew about the lead in Flint’s water. He did nothing. As a result, hundreds of children were poisoned. Thousands may have been exposed to potential brain damage from lead. Gov. Snyder should resign,” he said in a statement. "Because of the conduct by Gov. Snyder’s administration and his refusal to take responsibility, families will suffer from lead poisoning for the rest of their lives. Children in Flint will be plagued with brain damage and other health problems. The people of Flint deserve more than an apology."

Sanders' main rival for the Democratic presidential nomination, Hillary Clinton, has also called for an explanation of what Snyder's administration knew and said that the situation was "unconscionable." The former Secretary of State has also called on Michigan to pay for water purchases from Detroit for Flint residents until their water is safe again. Clinton also sent Amanda Renteria, her national political director, and Mike Schmidt, a policy adviser, to Flint this week to meet with Flint Mayor Karen Weaver about the situation.

David Murray, a Snyder spokesman, said that the governor didn't become aware of the blood lead issue until October 1 and that Sanders' demands didn't contribute to solving the water issue now.

"The best thing for the people of Flint is that every effort is focused on solving this emergency, getting the aid needed to help the residents, and ensuring that clean drinkable water is restored to the city," he said in a statement. "Political statements, and finger pointing from political candidates not involved in finding solutions for Flint, only serve to distract from solving this crisis."

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