President Barack Obama will next week travel to Flint, Michigan, where a crisis over tainted water has become a focus of the 2016 election campaign, the White House said Wednesday.

Responding to a letter from eight-year-old Flint resident Mari Copeny, Obama said he would visit the majority African American northern city on May 4.

"I want to make sure people like you and your family are receiving the help you need and deserve," Obama wrote.

Republican and Democratic presidential candidates have used the Flint crisis to trade barbs about the size, role and failings of local and federal governments.

More than 8,000 children are believed to have drunk water that contained harmful levels of lead.

The tainted water stemmed from a decision to shift Flint's water source from the Detroit River to the Flint River as part of cost-cutting measures ordered by state Governor Rick Snyder, a Republican who has consistently resisted calls to quit.

Experts believe the chemical-laced Flint River water corroded lead pipes, allowing large amounts of the chemical element to leach into the city's water.

The state attorney general has filed criminal charges against a city official and two state regulators for allegedly falsifying tests and tampering with evidence.

In the heart of America's rustbelt, Flint is at the crossroads of many of the issues that have dominated the 2016 election cycle -- foreign trade, environmental standards, the economy and the gap between rich and poor.

Democratic candidates Hillary Clinton and Bernie Sanders even held a presidential debate in Flint ahead of the Michigan primary in March.

Sanders' strident message on the need to address income inequality narrowly won the day in the Democratic primary.

But the state is set to be a battle ground in the general election.

Donald Trump's populist message targeting disaffected white voters propelled him to win Michigan's Republican primary.

Obama is likely to use the trip to show Flint residents that the federal government is listening to them, and implicitly or explicitly, that the fault lies elsewhere.

A presidential visit will also energize his supporters ahead of the November 8.