By Keith Laing - 03/08/12 03:18 PM EST
The amendments to be considered include a measure from Sen. John Hoeven (R-N.D.) that would authorize the Keystone XL pipeline without President Obama's approval, and one from Sen. Ron Wyden (D-Ore.) that would block exporting oil brought into the country through the controversial pipeline.
Also to be considered is an amendment from Sen. David Vitter (R-La.) to extend oil and gas drilling permits in the Outer Continental Shelf, and one from Sen. Bob Corker (R-Tenn.) to reduce the 2013 discretionary spending cap.
Several of the measures will require 60 votes to be approved.
Democrats have framed relenting on amendments as the only way to move forward in the Senate on the transportation bill, which even Republican leaders in the House have publicly acknowledged could end up forming the basis of a final authorization measure that becomes law.
"I was hoping we wouldn't have to face convoluted amendments that are completely non-germane amendments, but they are insisting on them, so we'll have to deal with those," Sen. Barbara Boxer, the chairwoman of the Senate Environment and Public Works Committee, who has shepherded the transportation bill to the Senate floor, said in a press conference Wednesday.
"It probably would be rolling back Clean Air Act rules," Boxer said of the amendments to the highway bill. "I can't imagine why anyone would want to do that, but there are some that want to do that."
The Senate began consideration of the highway bill amendments at 9:30 Thursday morning. The chamber is expected to resume debating the measure at about 10:45.
— Pete Kasperowicz contributed to this report.