Read more of our articles on Flint’s water emergency here.

Flint, Michigan, has been in a state of emergency for more than a month as residents deal with highly lead-contaminated water, yet the field of presidential candidates didn’t start talking about the issue until recently.

Michigan Gov. Rick Snyder (R) apologized to residents of Flint in a State of the State address Tuesday evening, in which he promised to tackle the problems plaguing the community after state officials switched its water supply source to the Flint River in an effort to save money. When the state Department of Environmental Quality failed to properly treat the water, lead leached into it from pipes and fixtures.

Pointing to failures within his own administration to properly address the emergency, Snyder expressed regret that the government hadn’t done more.

“No citizen of this great state should endure this kind of catastrophe. Government failed you—federal, state and local leaders—by breaking the trust you place in us,” said Snyder. “I’m sorry most of all that I let you down. You deserve better. You deserve accountability. You deserve to know that the buck stops here with me.”

The governor’s comments came just after news broke that the EPA had blamed “failures and resistance at the state and local levels” for the lack of proper response to contaminated water in Flint.

For weeks, Snyder has faced growing criticism—and calls for his resignation—over charges that he and his administration are to blame for the public health emergency in Flint. Yet even as the National Guard arrived in Michigan to help distribute water to the 30,000 homes, many presidential candidates remained surprisingly silent on the situation.

As the seriousness of what is occurring in Flint became more apparent and garnered more national news, Democratic candidates began to express their outrage over the government’s failures.

Clinton offered one of the more robust responses to the crisis, having spent much of the last two weeks speaking out on the issue and directly criticizing Gov. Snyder’s failure to properly respond.

Last week, Clinton dispatched two of her aides to Flint to meet with Mayor Karen Weaver, a move that earned her the mayor’s endorsement for president.

Speaking on a conference call set up by the campaign, Weaver said that Clinton was the only candidate from either party that had directly reached out to the city.

“As far as what Hillary Clinton has done, she has actually been the only—the only—candidate, whether we’re talking Democratic or Republican, to reach out and talk with us about, ‘What can I do? What kind of help do you need?'” Weaver explained, according to the Huffington Post.

Clinton’s decision to send her aides directly to the area was preceded by a series of statements demanding action be taken to help Flint’s residents.

“There is no excuse for what’s happening in Flint. A city of 99,000 people—a majority of them African-American, 40% in poverty—spent nearly two years drinking and bathing in water that we now know contained dangerous amounts of lead,” Clinton said in one statement on the matter. “I’m calling on the state of Michigan to finance water purchases from Detroit until safe drinking water is fully restored in Flint.”

In Sunday’s Democratic debate, Clinton brought up Flint during her closing statement after the moderators failed to mention it. “I think every single American should be outraged,” Clinton said. “We’ve had a city in the United States of America where the population, which is poor in many ways and majority African-American, has been drinking and bathing in lead-contaminated water. And the governor of that state acted as though he didn’t really care.”

Former Maryland Gov. Martin O’Malley, meanwhile, first addressed the crisis in a series of tweets on January 15, calling the matter heartbreaking and blaming elected officials who made “reckless decisions and “did nothing” to help the children of the city:

As a father, the Flint water crisis breaks my heart—and as a mayor & gov, it makes me spitting mad. This should not happen in America. (1/2)

— Martin O’Malley (@MartinOMalley) January 15, 2016

Reckless decisions exposed children in Flint—many poor and black—to poison. Elected officials did nothing. It’s time for justice. (2/2)

— Martin O’Malley (@MartinOMalley) January 15, 2016

O’Malley took his criticism even further in a video posted Monday by NowThis News. When asked whether Gov. Snyder should resign, the Democratic candidate replied, “It would appear that somebody sure as hell should.”

“Lead poisoning is something that has plagued poor communities in cities and people of color, and the notion that … our own government or that a local municipal government would be knowingly trying to cover something like this up is really appalling,” O’Malley went on, asserting that whoever knew about the situation and failed to stop it should resign.

Bernie Sanders also pushed back against officials in Michigan over the weekend, releasing a statement on Saturday urging Gov. Snyder to step down.

“There are no excuses. The governor long ago knew about the lead in Flint’s water,” said Sanders. “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.”

Sanders doubled down on his call the next day during the Democratic debate, telling viewers, “A man who acts that irresponsibly should not stay in power.”

In contrast, Republican presidential candidates have failed to address the issue at all until this week.

When asked for comment on Flint by a reporter at a campaign stop in New Hampshire on Monday, Sen. Marco Rubio (R-FL) claimed that it wasn’t something he knew enough about to speak on.

“It’s just not an issue we’ve been quite frankly fully briefed or apprised of in terms of the role the governor has played and that state has played in Michigan on these sorts of issues,” said Rubio, who also noted his belief that “the federal government’s role in some of these things [is] largely limited unless it involves a federal jurisdictional issue.”

Donald Trump similarly evaded addressing the crisis when confronted about it.

“It’s a shame what’s happening in Flint, Michigan. A thing like that shouldn’t happen,” Trump said Tuesday, according to the Wall Street Journal. “But again, I don’t want to comment on that.”

Ben Carson condemned local and federal officials for their response to Flint, but stopped short of casting any blame on Gov. Snyder or his administration.

“Unfortunately, the leaders of Flint have failed to place the well-being of their residents as a top priority,” Carson said in a Tuesday statement to the Huffington Post.

“The people deserve better from their local elected officials, but the federal bureaucracy is not innocent in this as well. Reports show that the Environmental Protection Agency knew well-beforehand about the lack of corrosion controls in the city’s water supply, but was either unwilling or unable to address the issue,” Carson continued.

Ohio Gov. John Kasich completely backed Snyder’s response to Flint on Tuesday, reportedly pointing out that Snyder had already moved in the National Guard and expressing confidence he “will manage this appropriately.”

Ted Cruz called the crisis “an absolute travesty,” demanding accountability for those poisoned by the water.  

“It is a failure at every level of government, a failure of the city officials, a failure of the county officials, and the men and women of Michigan have been betrayed,” Cruz said at a Tuesday press conference in New Hampshire.

“Every American is entitled to have access to clean water, and to all the children who have been poisoned by government officials, by their negligence, by their ineptitude, it’s heartbreaking,” Cruz said.

Although he didn’t specifically criticize the state’s response, Cruz called for officials to take responsibility for their mistakes, asserting, “There needs to be accountability as to why dirty water, poisoned water was given to a community that did not deserve this.”