Sen. Debbie Stabenow (D-Mich.) left, and Sen. Gary Peters (D-Mich.) discuss proposed legislation to help Flint, Mich. with their current water crisis. (Alex Brandon/AP)

Hillary Clinton and Bernie Sanders have clashed over Wall Street reforms, gun control, free trade and more. But in recent weeks, the two presidential candidates, along with their fellow Democrats on Capitol Hill, have found an issue they can all rally around: the drinking-water crisis in Flint, Mich.

Clinton sent top campaign aides to Flint in mid-January and declared herself “outraged” by the situation. Sanders followed with an early call for the resignation of Republican Gov. Rick Snyder, who has acknowledged that his administration botched the issue.

This week, the issue swept Capitol Hill, with House overseers grilling government officials and Senate Democrats voting Thursday to derail a major energy bill over a request for emergency aid.

And it was announced Thursday that Clinton and Sanders will debate next month in the impoverished, majority-black city of 100,000, where residents continue to rely on bottled water amid fears of widespread lead poisoning. Clinton’s aides also said Thursday that she would take a break from campaigning in New Hampshire to visit the city Sunday.

The House Oversight and Government Reform committee held an outrage-filled hearing on Feb. 3 about the drinking water crisis in Flint, Mich. (C-SPAN)

The lawmakers who are trying to address the crisis insist they are not seeking to politicize it, but it has become clear that Democrats see Flint as a potent symbol of the perils of Republican governance — one they will return to throughout the election year.

“The reality is, there’s a philosophical difference about the appropriate role of government, and we see what happens when we don’t have basic safety standards and quality standards for our water,” said Sen. Debbie Stabenow (D-Mich.), who is leading efforts to secure federal aid for the city. “We will have a lot to say about that later.”

The emerging politics of the Flint crisis were laid bare on Capitol Hill this week, after Stabenow and Michigan’s other senator, fellow Democrat Gary Peters, proposed to use the energy bill as a vehicle for as much as $600 million in emergency aid to Flint. Most would be used to replace lead pipes that corroded because of state-level decisions to switch water sources; the rest would fund a center to monitor and treat victims of lead poisoning.

The Democrats reached a tentative deal with the bill’s Republican sponsor, Sen. Lisa Murkowski of Alaska, to address concerns about the cost and structure of the aid. But GOP senators raised concerns about the compromise, saying it could create a precedent for federal aid for other incidents that they see as a largely state and local responsibility.

Sen. John Cornyn (R-Tex.), the No. 2 Senate Republican, on Thursday called the Democrats’ proposal a “$600 million earmark” that seeks money that the state does not have a plan to spend. He accused Democrats of being more interested in scoring political points than in crafting a workable solution to the crisis.

“In the immortal words of Rahm Emanuel . . . never let a crisis go to waste,” Cornyn said, quoting the Chicago mayor and former White House chief of staff. “That is what’s happening here. . . . It’s not even a good-faith effort to solve a problem. It’s just trying to put on a show vote and embarrass people.”

A key procedural vote that would end debate on the energy bill and set up a vote on final passage failed 50 to 46, with all but five Democrats voting to block the legislation pending a deal on aid to Flint. At least one Republican senator in a close reelection contest was immediately criticized by a Democratic opponent for voting to proceed.

The Democratic lawmakers inside the Capitol who have been working to forge a compromise on aid have been mostly careful not to frame the issue in terms of race or class. Senate Minority Leader Harry M. Reid (D-Nev.), for instance, said in an interview that aid for Flint was a matter of basic fairness considering the disaster assistance Congress has historically rendered to areas in need.

“These people are just screwed. I mean, they really, really are,” he said.

That restraint has not been in evidence on the campaign trail. “I’ll tell you what: If the kids in a rich suburb of Detroit had been drinking contaminated water and being bathed in it, there would’ve been action,” Clinton said at a Jan. 17 debate.

Given the gravity of the crisis and Michigan’s likely status as a presidential swing state, Flint stands to remain a fixture of presidential politics for months, said Benton Strong of the Center for American Progress Action Fund, a progressive advocacy group.

The crisis, he said, will remain a vivid illustration of America’s racial and economic disparities and of the effects of the fiscal austerity policies favored by GOP candidates.

“The whole philosophy leads to big gaps in our ability to tackle challenges,” Strong said. “Flint is a frustratingly obvious and predictable example of what can happen when this philosophy carries the day.”

In one of the few remarks on the GOP presidential trail about the issue, Sen. Ted Cruz (R-Tex.) on Wednesday fingered the “one-party government control of far-left Democrats.” Republicans on Capitol Hill, meanwhile, have said they are committed to helping Flint but say they want to be careful in their response.

“You have to ascertain the facts, and then you have to see . . . which level of government is the proper level of government to take the lead,” House Speaker Paul D. Ryan said Thursday.

The Flint issue could play an outsize role in motivating African Americans to turn out for Democratic candidates in November. The Congressional Black Caucus delivered a letter Thursday to Senate Majority Leader Mitch McConnell (R-Ky.) urging action on an aid package.

“Black voters need to understand that government matters and elected officials matter, and you do not have control of your destiny unless you are involved in the political process, and Flint is a perfect example,” the caucus’s chairman, Rep. G.K. Butterfield (D-N.C.), said Thursday. “We will be using this as an example, not as an organizing tool but just as an example, of how government is very much involved in the life of every American.”

Anne Gearan contributed to this report.