WASHINGTON — Sen. Tom Coburn called Tuesday for an investigation into how an earmarked road project for Florida was changed in the 2005 highway bill after it was approved by the House and Senate but before it was sent to the president for his signature.

Coburn, R-Muskogee, told Senate Republican leader Mitch McConnell, R-Ky., that he would block consideration of a bill making some changes to the 2005 highway bill unless the investigation is included.

"Because secret, improper and unauthorized changes to congressionally passed legislation call into question the integrity of our entire constitutional and legislative process, I believe a full and open investigation into this matter is necessary to restore the integrity of both the U.S. Congress and the Constitution,” Coburn told McConnell in a letter.

The controversy over the "Coconut Road” project has been simmering for months, in part because of a New York Times story that linked the $10 million earmark to a group of developers who held a fundraiser for Rep. Don Young, the Alaska Republican who helped write the highway bill.

Who spotted the change?

A group called Taxpayers for Common Sense, which scrutinizes earmarks, discovered that the $10 million had been allocated for widening a portion of Interstate 75 when the House and Senate gave final approval to the 2005 highway bill. The project was changed, however, to build a road favored by the Florida developers before the bill was sent to the president.

Such a change would require approval by the House and Senate to be constitutional, Coburn said.