UPDATE 4-Trump vetoes lawmakers' measure against border wall

President Donald Trump on Friday vetoed a measure to terminate his emergency declaration over a border wall, striking back at Republican and Democratic lawmakers who opposed the controversial move with the first veto of his presidency. While Congress is unlikely to muster the votes to override the veto, the rebuke from some members of his own party left Trump politically wounded, at least temporarily, as immigration and his planned wall along the U.S. southern border become a flashpoint again in the 2020 presidential campaign.

The bipartisan vote in the Senate on Thursday approving the measure was a slap at Trump over his decision to circumvent Congress and take money already designated for other programs to pay for his barrier along the U.S.-Mexico border. Twelve of Trump's fellow Republicans joined Democrats to pass the measure to end the emergency declaration.

Before issuing the veto, Trump again said there was a tremendous national emergency, while U.S. Attorney General William Barr said the action the president had taken was legal. The emergency declaration is being challenged in court as an unconstitutional usurpation of Congress' power of the purse.

Trump was flanked by border officials and people who have had family members killed by someone who was in the United States illegally as he issued the veto during an Oval Office signing ceremony. The president has said he wants a wall to prevent immigrants from crossing into the United States illegally. Democrats deny there is an emergency at the border, saying border crossings are at a four-decade low.

Trump thanked Republican senators who voted for his declaration in a Twitter post earlier on Friday. "Watch, when you get back to your State, they will LOVE you more than ever before!" he said. The president made a border wall a central promise of his 2016 campaign for the White House. He initially insisted that Mexico would pay for the wall but it has declined to do so. Last year, Trump forced a government shutdown over an impasse with Congress over funding for the barrier.

When a deal to prevent another shutdown did not give him the funding he requested, Trump declared a national emergency, redirecting funds that were allocated for other projects to build the barrier instead. (Reporting by Jeff Mason and Roberta Rampton in Washington; editing by Dan Grebler and James Dalgleish)