Senator Mitt Romney, R-Utah, Thursday declared himself against President Trump's emergency declaration to secure the southern border.

“I will vote today for the resolution of disapproval," Romney said in a statement. "This is a vote for the Constitution and for the balance of powers that is at its core. For the Executive Branch to override a law passed by Congress would make it the ultimate power rather than a balancing power."

Romney joins Sen. Rand Paul, R-Ky., and five other GOP senators who will vote for H.J.Res.46, the Emergency Declaration resolution of disapproval.

GOP SENATORS APPEAR READY TO BLOCK TRUMP DECLARATION

Earlier this month, Senate Majority Leader Mitch McConnell, R-Ky. said the resolution would likely pass and be vetoed by the president.

Romney made it clear that his vote wasn't about the securing the border with Mexico, but rather overreach by the Executive Branch.

“This is not a vote against border security. In fact, I agree that a physical barrier is urgently needed to help ease the humanitarian crisis at the southern border, and the administration already has $4.5 billion available within existing authority to fund a barrier – even without an emergency declaration," Romney said in the statement.

TRUMP SCUTTLES DEAL THAT WOULD AVOID SENATE REBUKE

“I am seriously concerned that overreach by the Executive Branch is an invitation to further expansion and abuse by future presidents. We experienced a similar erosion of congressional authority with President Obama’s unilateral immigration orders – which I strenuously opposed. In the case before us now, where Congress has enacted specific policy, to consent to an emergency declaration would be both inconsistent with my beliefs and contrary to my oath to defend the Constitution.”

Tuesday a group of Republican senators introduced legislation by Sen. Mike Lee, R-Utah, limiting presidential powers to declare emergencies.

The Associated Press contributed to this report.