Last week, the House of Representatives voted to overturn President Donald Trump's national emergency declaration that would free up funds to build his highly anticipated border wall. Now, it looks as though the Senate may vote in a similar fashion. And the person who will be the deciding vote is none other than Sen. Rand Paul (R-KY).

Paul told a crowd of Republicans he couldn't support the president on the declaration, the Bowling-Green Daily News reported.

"I can’t vote to give extra-Constitutional powers to the president. I can’t vote to give the president the power to spend money that hasn’t been appropriated by Congress. We may want more money for border security, but Congress didn’t authorize it. If we take away those checks and balances, it’s a dangerous thing," Paul explained.

Paul joins Sens. Susan Collins (R-ME), Lisa Murkowski (AK) and Thom Tillis (NC) who said they will vote to overturn Trump's emergency declaration. If these four Republicans join the Senate's 47 Democrats in opposition to the declaration, President Trump may be forced to issue a veto in order to obtain the funding for his wall.

If Trump decides to go through with vetoing the decision, he could face backlash from fellow Republicans, something Sen. Lamar Alexander (R-TN) warned about on Thursday, POLITICO reported.

“He’s got sufficient funding without a national emergency, he can build a wall and avoid a dangerous precedent,” Alexander told reporters. “That would change the voting situation if he we were to agree to do that.”

This will definitely be something to watch as both parties finalize their votes.