The 53-36 vote was well short of the two-thirds required to overturn the veto. The vote mirrored ones last month and in March in which a number of Republicans broke with Trump in defending lawmakers' power of the purse. The military projects in question included base schools and target ranges.
In February, Trump declared the security situation along the border a national emergency. That decision enabled him to take up to $3.6 billion from such projects to finance wall construction beyond the miles that lawmakers have been willing to fund.
Democrats reacted with outrage and some GOP senators opposed Trump as well. Top Republicans such as Majority Leader Mitch McConnell of Kentucky had urged Trump not to do it. But once Trump acted, McConnell and others fell into line even as 10 Republicans broke with Trump on Thursday's vote.
"The president's emergency declaration is an unconstitutional power grab. Congress has not fully funded his requests for border wall funding," said Sen. Tom Udall, D-N.M. "But this president will not accept Congress's judgment. Or our constitutional authority. His emergency declaration is an exercise of power that is just not his under the Constitution."
Trump has obtained just over $3 billion for border barrier construction by working through regular congressional channels, subject to limitations imposed by lawmakers. He has used various transfer and emergency authorities to shift almost $7 billion more from the emergency declaration, a forfeiture fund containing money seized by law enforcement, and funding for military counterdrug activities.
Last week, a federal judge in Texas ruled that Trump had exceeded his authority in reallocating the money for military construction to the border wall. The Supreme Court in July issued a stay on a ruling by a California court that blocked Trump from carrying out the maneuver.
The Pentagon recently identified $3.6 billion worth of military construction projects it's willing to kill in order to build 175 miles (282 kilometers) of border wall. The projects included a $63 million middle school in McConnell's state of Kentucky, though most of the projects are outside the continental U.S.