(CNN) Sen. Thom Tillis will be among those Republican senators to vote in favor of a resolution against President Donald Trump's declaration of a national emergency at the border, the North Carolina Republican made public Monday, increasing the chances that the resolution will be sent to the White House.

Tillis, who is up for re-election in 2020, wrote in an op-ed for The Washington Post that while he favors border security, he is concerned the President has overreached with the national emergency declaration.

"As a U.S. senator, I cannot justify providing the executive with more ways to bypass Congress," he wrote. "As a conservative, I cannot endorse a precedent that I know future left-wing presidents will exploit to advance radical policies that will erode economic and individual freedoms."

The measure would block the President from accessing some funds to construct a wall on the southern border, and Trump has promised to veto it should it reach him, which would be his first presidential veto since assuming the office.