Washington - A Democratic representative has introduced the first formal article of impeachment against President Donald Trump. Representative Brad Sherman alleges Mr Trump committed obstruction of justice by firing former FBI Director James Comey amid agency investigations into Russian meddling in the US election. "Such conduct," Mr Sherman writes in the article, "warrants impeachment and trial, and removal from office." The Constitution allows impeachment in the case of "treason, bribery, or other high crimes and misdemeanours". Obstruction of justice is a felony offence. To take effect, however, articles of impeachment must pass the House by a majority vote – an unlikely outcome in today's Republican-controlled chamber. So far, only one other Democrat – Texas Representative Al Green – has publicly expressed support for impeachment proceedings. When Mr Sherman started circulating a draft article last month, fellow Democratic Representative Michael Capuano reportedly stood up at a party meeting and denounced him as selfish. In a statement issued Wednesday, Mr Sherman said he does not expect impeachment to happen immediately. Instead, he hopes the article will inspire an "intervention" in the White House, and encourage the executive branch to control its "uncontrollable impulses". If not, he said, Republicans will eventually begin to support the impeachment effort.