US President Donald Trump on Friday vetoed legislation attempting to block his declaration of a national emergency regarding US-Mexico border wall spending.

The US Senate voted 59-41 this week to reject Trump’s declaration of a national emergency, exercised under the National Emergencies Act, to appropriate an additional $3.6 billion in funding to build a wall along the Mexican border. Under the Act, Congress has the opportunity to terminate the national emergency via a joint resolution. The House of Representatives passed the joint resolution in February. All 45 Democratic Senators, both Independent Senators, and 12 Republican Senators voted to terminate the national emergency.

This veto marks the first use of Trump’s veto power, stating that it was his “duty” to veto it. In a statement to the House of Representatives relaying his reasoning for the veto, Trump said:

[R]ecent statistics published by U.S. Customs and Border Protection (CBP) and explained in testimony given by the Secretary of Homeland Security on March 6, 2019…our porous southern border continues to be a magnet for lawless migration and criminals and has created a border security and humanitarian crisis that endangers every American. This situation on our border cannot be described as anything other than a national emergency, and our Armed Forces are needed to help confront it. Every day, the crisis on our border is deepening, and with new surges of migrants expected in the coming months, we are straining out border enforcement personnel and resources to the breaking point. H.J. Res. 46 ignore these realities. It is, therefore, my duty to return it…without my approval.

The House is expected to hold a veto-override vote on March 26, but currently they do not have enough votes to be successful.