A Senate ethics panel has dismissed charges that a Louisiana senator engaged in bribery by blocking the Interior secretary's pay raise until the agency accelerated its approval of offshore drilling permits.

But the Select Committee on Ethics said Sen. David Vitter's (R-La.) decision to block a proposal to bump Interior Secretary Ken Salazar's salary by $19,600 -- making it equal to other Cabinet secretaries -- was unprecedented and inappropriate and could erode trust in the legislative branch.

"While the committee found there was no substantial credible evidence that you violated the law or Senate rules, it did conclude that it is inappropriate to condition support for a secretary's personal salary increase directly on his or her performance of a specific official act," committee Chairwoman Barbara Boxer (D-Calif.) and Vice Chairman Johnny Isakson (R-Ga.) wrote in a letter to Vitter today.

The committee in a separate letter to Senate colleagues clarified that future actions would be considered "improper conduct reflecting discreditably on the Senate."

Vitter last May said he would block a bipartisan proposal to raise Salazar's pay until the pace of deepwater oil and gas permitting in the Gulf of Mexico returned to levels before the April 2010 Macondo spill -- six permits per month, according to his office (Greenwire, May 25, 2011).

The panel said there is no clear Senate guidance on such behavior but noted that Vitter's demand put Salazar in an awkward position.

"While senators have long used holds on nominations to help persuade administrations to carry out or change policies, tying an incumbent secretary's personal salary directly to his or her performance of a specific official act is different, places the secretary in a precarious and potentially untenable position, and undermines a basic principle of government service," Boxer and Isakson wrote.

Vitter's office issued a statement today saying that the committee's decision "validated" the senator's decision to block Salazar's pay and that he intends to continue blocking pay raises in the future.

"The bipartisan committee completely dismissed this complaint today," Vitter said. "I'm glad that I killed Ken Salazar's salary increase -- he has completely failed us on energy policy."

The government watchdog group Citizens for Responsibility and Ethics in Washington last June asked the panel to investigate whether Vitter's move amounted to bribery. CREW Executive Director Melanie Sloan today said Vitter deserved more than a warning from the panel.

"It's now the second time the Ethics Committee needed to warn Mr. Vitter that next time he's in big trouble," Sloan told E&ENews PM, referring to an earlier dismissal of a complaint connecting Vitter to a prostitution ring. "You wouldn't think senators would need guidance that they can't engage in bribery or extortion, but apparently the Ethics Committee believed they do."

Salazar is paid less than other secretaries because of a provision in the U.S. Constitution that bars senators from becoming the recipients of pay raises they supported as lawmakers. Salazar's term as senator from Colorado would have ended in January 2011, prompting the bipartisan proposal to increase his pay. He left the Senate in 2009 to join President Obama's Cabinet.

The former Colorado senator last May sent a letter to Senate leadership questioning the ethics of Vitter's move but asking that efforts to increase his salary be set aside.

"Our oversight and regulation of offshore energy production is -- and will continue to be -- guided by principles of integrity, the public interest and much-needed safety and environmental standards," Salazar told Majority Leader Harry Reid (D-Nev.) and Minority Leader Mitch McConnell (R-Ky.) at the time.

The Ethics Committee said regardless of who the next Interior secretary is, his or her salary will also be $19,600 less than that of other Cabinet heads, who earn roughly $200,000 a year.