The head of the Environmental Protection Agency is struggling to show she did the right thing when it comes to the water crisis in Flint, Mich., as GOP lawmakers prod her to resign.

"Are we doing our job on oversight as effectively as we need to?" asked EPA Administrator Gina McCarthy at a breakfast held Tuesday by the Christian Science Monitor. "We're exploring those issues, and our Office of Inspector General is in the middle of doing an investigation. That was at my request. They are doing an audit of our entire oversight in the region."

EPA critics say the agency mishandled the water-contamination crisis in Flint, arguing that it was too slow to act after finding the water supply in the city was contaminated by lead.

That has led to a growing number of lawmakers questioning McCarthy's fitness to lead the agency. Rep. Jason Chaffetz, R-Utah, chairman of the House Oversight Committee, asked McCarthy why she has not resigned at a recent hearing on the water crisis.

Rep. Elijah Cummings, D-Md., said the EPA clearly should have done more. "The EPA should have done more, they should have rushed in sooner to rescue the people of Michigan from [Michigan] Gov. [Rick] Snyder's vindictive administration and his utter incompetence at every level," he said during last month's series of hearings on the crisis.

Cummings told Snyder he must resign. Cummings also said there is something terribly wrong with the EPA's Midwest Region 5 headquarters. The head of the office resigned after divulging that the EPA knew the water was unsafe to drink for months but did not warn the residents of Flint, giving deference to the state that also chose to do nothing.

The water crisis has become a national scandal that has found its way into the 2016 presidential debate. The lead scandal stemmed from a decision made by a state-appointed emergency manager, who moved the city's water supply from its normal route to the polluted Flint River to save money. The acidic nature of the river's water caused lead to leach from water pipes, contaminating the city's drinking water supply.

McCarthy recently said it was Michigan's fault in causing the water crisis, suggesting that the EPA's decision not to alert residents sooner is not at question.

"I wasn't trying to deflect blame — simply get all the facts on the table that it was clearly Michigan and the emergency manager that made decisions that didn't make sense," McCarthy said.