Bernie Sanders speaks during a recent campaign event at Wartburg College in Waverly, Iowa. (Photo by Scott Morgan/Reuters)

CHARLESTON, S.C. -- Democratic presidential hopeful Bernie Sanders on Saturday called for Michigan Gov. Rick Snyder (R) to resign amid mounting criticism of his administration’s slow response to a crisis over lead contamination in Flint’s drinking water.

“There are no excuses,” Sanders said in the statement. “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."

The statement came as the senator from Vermont prepared for a full weekend of political events in South Carolina, including a high-stakes debate Sunday night with former secretary of state Hillary Clinton and former Maryland governor Martin O’Malley.

Clinton spoke out about the situation earlier this week, saying she was "outraged" by Snyder's delay in seeking federal assistance to address the problem and sending two staffers to the city.

"This is infuriating to me," Clinton said during an appearance on MSNBC's "The Rachel Maddow Show." "I care deeply about this issue. We know it has effects on behavior and educational attainment."

[In Flint, bad tap water runs politically deep]

Michigan’s attorney general opened an investigation Friday into the poisoning of Flint’s water supply at least a year and a half before it was addressed by state officials -- a situation that has now left an economically challenged city of 100,000 people unable to use tap water for drinking or bathing.

Snyder this week apologized for the lapse and declared a state of emergency. Michigan’s top environmental regulator has resigned over the episode, which took place after the city switched water supplies in 2014 while a new pipeline was under construction.

 “The people of Flint deserve more than an apology," Sanders said.