WASHINGTON (Reuters) - U.S. President Donald Trump solicited foreign interference to boost his re-election chances, undermined national security and ordered an "unprecedented" campaign to obstruct Congress, Democrats said on Tuesday in a report that lawmakers will use as the basis of any formal impeachment charges.

In the 300-page report, Democrats leading the House of Representatives Intelligence Committee levelled allegations of sweeping abuse of power by Trump, saying he used U.S. military aid and the prospect of a White House visit to pressure Ukrainian President Volodymyr Zelenskiy to undertake investigations that would benefit Trump politically.