Senators voted 64-28 to add the amendment to a bill making technical corrections to the 2005 highway bill, despite opposition from Speaker Nancy Pelosi (D-Calif.), who on Thursday said the House ethics committee, and not Justice, should investigate the matter.

The $10 million earmark for the Coconut Road interchange in Florida was placed in the massive 2005 highway bill after the House and Senate passed the bill but before it reached the president’s desk. The original language called only for improving and widening Interstate 75 in Ft. Myers, Fla.

The measure calling for the Justice investigation was sponsored by Sen. Barbara Boxer (D-Calif.). Asked about that proposal, Pelosi said: “We have an ethics committee.”

Pelosi denied telling the Senate that an amendment calling for an investigation into the earmark would serve as a poison pill and sink the technical corrections bill. Senators have said the House has threatened to kill the underlying bill if the Senate attached an amendment convening a congressional inquiry into the matter.

Some House Republican leaders previously said they oppose any congressional action directing the Justice Department to launch a criminal investigation.

The Boxer amendment was a reaction to an initiative by Sen. Tom Coburn (R-Okla.), who has offered his own amendment to convene a bicameral select committee with subpoena power to investigative the earmark. The Senate is also expected to vote on Coburn’s measure this afternoon.