The US Senate Democratic leader Chuck Schumer has sent a letter to the US Secretary of State Mike Pompeo warning that he will strongly oppose any US-UK trade deal that undermines the Good Friday Agreement or facilitates a return to a hard border.
In the letter, Senator Schumer also tells the Trump administration to stop over-promising an "unconditional and unrealistic" post-Brexit trade agreement with the United Kingdom.
Chuck Schumer says he will work with the US Speaker of the House Nancy Pelosi and members on both sides of the political divide, in both chambers of Congress to block any deal that threatens the Good Friday Agreement.
Last week, Ms Pelosi reiterated her opposition to any trade deal that undermines the Good Friday Agreement warning there would be "no chance" of such a deal being passed by Congress.
She issued a statement on the matter following comments from US National Security Adviser John Bolton that the UK would be "front of the trade queue" for a new trade agreement with the US after Brexit.
In his letter today, the US Senate Minority Leader Chuck Schumer said that the notion that America would endorse a policy or agreement that undermines the success of the Good Friday Agreement is profoundly counterproductive and unleashes the potential for a return to violence.
"Plainly stated, America should not be in the business of handing out a blank cheque that bankrupts the peace, security, self-determination and shared prosperity precipitated by the Good Friday Agreement.
"America's policy should be to realise the full potential of the Good Friday Agreement, not to erode it or entertain the possibility of a return of a hard border or direct rule," he wrote.