D.C. Mayor Vincent Gray on Tuesday sought to curb political donations by existing or aspiring city contractors as part of his long-awaited proposal to overhaul the District’s campaign finance practices, even as federal authorities investigate the Gray campaign’s dealings with a man who won hundreds of millions of dollars in city contracts.

“It’s one of the most important issues that we face in the city at this stage,” said Gray, who emphasized that he wants the District government to avoid the appearance of corruption. “It’s at the highest level [of priority.]”