WASHINGTON - Senators from across party lines in the United States have backed an amendment opposing Donald Trump's plan to pull troops out of Syria and Afghanistan, in a strong rebuke of the Republican president's decision.

The text, which was passed on Monday by a majority of 70 to 26, says the troop withdrawal could allow the Islamic State of Iraq and the Levant (ISIL, also known as ISIS) group and al-Qaeda to re-group and destabilise both countries.

The measure was sponsored by Mitch McConnell, the Republican leader of the Senate who said last week it "would acknowledge the plain fact that al-Qaeda, ISIS and their affiliates in Syria and Afghanistan continue to pose a serious threat to our nation".

Al Jazeera's Mike Hanna, reporting from Washington, DC, said the result of the vote constituted "a sharp, bipartisan rebuke from the Senate of Trump".

The amendment, opposed by only three of the 53 Senate Republicans, will eventually be incorporated into a broader security bill on the Middle East which will be voted on later this week.

"Importantly, too, it's then got to go to the House of Representatives, where other aspects of the wider bill are likely to receive stern opposition from the Democrat-controlled body," Hanna said. (FA)