WASHINGTON — A young Missouri student’s painting of civil unrest has sparked a proxy battle among lawmakers in the halls of the U.S. Capitol, between black Democrats concerned about what they call a legacy of unjust policing and several white Republicans who are defending law enforcement.

The tiff spiraled out of control Tuesday, with House Republicans acting on two separate occasions to pull the artwork down from a tunnel in the Capitol complex, after it was rehung by Rep. William Clay Jr., D-Mo., whose young constituent painted it.

The painting, by recent high school graduate David Pulphus, depicts a scene inspired by the 2014 events in Ferguson, Missouri, and other recent protests against police led by African Americans. Several figures are depicted as animals, and some pro-police activists have said the rendering evokes derogatory images of police as pigs.

It is part of a national art competition, one of 435 artworks chosen by local panels of artists to hang in the underground tunnel between the Capitol and the Cannon House Office Building.

Clay appeared in the tunnel with fellow members of the Congressional Black Caucus Tuesday morning to rehang the painting after it had first been removed Friday by Rep. Duncan Hunter, R-Calif., — who took it down, in a spokesman’s words, to “make a statement” about his support for law enforcement and delivered it to Clay’s office.

For more than two years, the national debate about the policing in African-American communities has largely bypassed Capitol Hill, which has been under the control of Republican lawmakers wary of wading into the controversy. Rather, it took an 18-year-old’s painting to unleash lawmakers’ passions.

Clay and others defended Pulphus’ right to free expression, and to have his views represented on the walls of the U.S. Capitol — a building, they pointed out, that contains numerous statues of Confederate leaders and other racist historical figure.

Clay said he was “not anti-police” and said his family included many law enforcement members. But he said that Pulphus had a right to express his impression of the struggles black Americans have experienced with police.

The painting hung in the Capitol for several months without incident before a conservative website, Independent Journal Review, wrote about it, and a Fox News personality highlighted it on air in late December.