Story highlights The bill mimics in large part a companion in the House from Rep. McCaul

The senators called the bill a "first step" in reforming the nation's immigration system

Washington (CNN) A top Senate Republican unveiled a border and immigration enforcement bill on Thursday with fellow GOP lawmakers that would invest $15 billion over four years in border security and help fund President Donald Trump's wall.

The bill from Senate Majority Whip John Cornyn of Texas would authorize the physical border wall and technological advancements at the southern border. It would also put into law Trump's desire to hire thousands more Border Patrol agents, immigration officers and judges and seeks to add resources to ports of entry and to local law enforcement in the border region, and would mandate a national entry-exit system for tracking people entering and leaving the US with biometric measurements.

The bill would not touch the structure of the US visa system or reform any of the legal immigration laws in the US, but the GOP senators backing it say border security must come first before a broader immigration measure goes forward.

But Cornyn emphasized that he viewed the bill as lawmakers leading on border security, not the way the White House has approached the issue.

He said the bill would be the opposite of a "one-size-fits-all solution" and emphasized that he favored it over an "ad hoc" approach.

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