Senate slaps down Trump border emergency; Republicans defect

President Donald Trump speaks during a meeting with Irish Prime Minister Leo Varadkar in the Oval Office of the White House, Thursday, March 14, 2019, in Washington. (AP Photo/ Evan Vucci)

Sen. Lamar Alexander, R-Tenn., tells reporters that he will vote for a resolution to annul President Donald Trump’s declaration of a national emergency at the southwest border, on Capitol Hill in Washington, Thursday, March 14, 2019. (AP Photo/J. Scott Applewhite)

Construction crews replace a section of the primary wall separating San Diego, above right, and Tijuana, Mexico, below left, Monday, March 11, 2019, seen from Tijuana, Mexico. President Donald Trump is reviving his border wall fight, preparing a new budget that will seek $8.6 billion for the U.S-Mexico barrier while imposing steep spending cuts to other domestic programs and setting the stage for another fiscal battle. (AP Photo/Gregory Bull)

WASHINGTON — In a stunning rebuke, a dozen defecting Republicans joined Senate Democrats on Thursday to block the national emergency that President Donald Trump declared so he could build his border wall with Mexico.