President Donald Trump has issued the first veto of his presidency, overruling Congress to protect his emergency declaration for border wall funding.

Flanked by law enforcement officials as well as the parents of children killed by people in the country illegally, Trump says "our immigration system is stretched beyond the breaking point" and calls the congressional action "dangerous" and "reckless."

A dozen Republicans joined with Senate Democrats on Thursday to back the joint resolution disapproving of Trump's emergency declaration. The House had passed the same resolution last month largely along party lines.

It is unlikely that Congress will have the two-thirds majority required to override Trump's veto.

Trump wants to use the emergency order to redirect billions in federal dollars earmarked for defense spending toward the southern border wall. It still faces several legal challenges in federal court.

The bill was hand-delivered to the White House around 5:30 p.m. Thursday evening. And Trump made clear how he plans to respond, tweeting the word "VETO!" in all-caps moments after Thursday's vote.

Thursday's vote was the first time Congress used its power to reject a presidential emergency order.

Trump wants to use his declaration to steer $3.6 billion more to border barriers than lawmakers approved. He had warned Republicans to stick with him on the vote. He said doing otherwise would be siding with Democratic House Speaker Nancy Pelosi. But several Republicans defied that warning.

Trump wants to steer $3.6 billion more to border barriers than lawmakers approved. The move is also being challenged in court.

U.S. Senator Jacky Rosen (D-NV) voted to terminate the declaration. 

“The President is on record saying that the emergency declaration was something he didn’t need to do; I agree, and that’s why I voted to overturn his unjustifiable attempt to circumvent Congress. The President’s emergency declaration is a violation of the Constitution’s separation of powers and is a gross overreach of power that completely undermines Congress’ constitutional appropriations authority. We need smart leadership and bipartisan immigration reform -- not an ineffective wall that will cost taxpayers billions.”

U.S. Senator Catherine Cortez Masto (D-NV) also voted to terminate the declaration.

“Our system of checks and balances is sacred. Congress passed the National Emergencies Act to allow presidents to declare national emergencies as a result of a threat to our country, or natural disaster, but it does not empower a President to create a crisis and use his power for political gain. Rather than accept the bipartisan border security funding passed by Congress, the President is trying to pull vital funds from military construction projects and anti-narcotic public safety task forces across the country; while doing nothing to address the real humanitarian crisis at the border. The President’s declaration is nothing more than an abuse of his power and my colleagues in the Senate have spoken in a bipartisan vote to rebuke President Trump and condemn this political power grab and waste of billions in taxpayer dollars.”  

(The Associated Press contributed to this report.)