FILE PHOTO: U.S. President Donald Trump sits for an exclusive interview with Reuters journalists in the Oval Office at the White House in Washington, U.S. December 11, 2018. REUTERS/Jonathan Ernst/File Photo

WASHINGTON (Reuters) - President Donald Trump on Thursday attacked Democrats again for not supporting his proposed border wall and said he would not sign any legislation that does not include his top agenda item, possibly threatening the spending bill that the U.S. Congress is negotiating to avoid a government shutdown.

“The Democrats, who know Steel Slats (Wall) are necessary for Border Security, are putting politics over Country. What they are just beginning to realize is that I will not sign any of their legislation, including infrastructure, unless it has perfect Border Security. U.S.A. WINS!” Trump, who leads the Republican party, wrote in an early morning tweet.