The US Senate delivered a surprisingly strong rebuke of President Donald Trump on Thursday, as several Republicans joined opposition Democrats in voting to terminate his declared emergency on the southern border.

A dozen Republicans supported ending Trump's emergency that he hoped would provide him cover to secure alternative government funding for his protective wall on the US-Mexico border denied to him by Congress.

But opponents warned that Trump's move smacked of executive overreach, and insisted a vote to curtail his authority would preserve the constitutionally mandated separation of powers in Washington.