Coburn and some other Republicans characterized the proposal as political cover for those who want to support the immigration bill, which may be set for a final Senate vote later this week.
Supporters of the bill have been hoping to get as many as 70 votes in the 100-member Senate to give the bill more momentum and put pressure on the House to take up immigration legislation. The border security amendment that advanced Monday is expected to add Republican support for the overall bill.
Sen. Chuck Schumer, D-N.Y., who helped craft the bill, said the Congressional Budget Office — a nonpartisan arm of Congress — had studied the proposed amendment and determined that it would reduce illegal immigration.
Schumer said the addition of 20,000 more border security agents would allow one to be stationed every 1,000 feet from San Diego to Brownsville, Texas.
At the White House, President Barack Obama told business leaders that the Senate bill — which he supports — was at a “critical point.”
“And I hope that we can get the strongest possible vote out of the Senate, so that we can then move to the House and get this done before the summer break,'' Obama said.