WASHINGTON—Democrats are crying foul after a GOP senator blocked a pay raise for Interior Secretary Ken Salazar in an effort to pressure him into approving more deepwater oil and gas drilling permits.

At issue is a move by oil state Sen. David Vitter, R-La., to not only block the almost $20,000 raise for Salazar last week but then offer to allow the raise to go forward if the Interior Department issues six new deepwater permits a month.

Salazar responded with a letter accusing Vitter of employing strong-arm tactics and of trying to coerce him into approving new drilling permits in order to get the raise.

Salazar said Vitter’s move amounted to “attempted coercion of public acts here at the Department” and asked that efforts to give him a pay raise be halted.

Salazar’s pay is lower than other Cabinet members because of an obscure constitutional requirement that blocks lawmakers who move to the executive branch from claiming pay raises they’ve voted on while in Congress.

Vitter blocked legislation last week to fix the disparity, saying he was keeping the “boot on the neck” of the department.

“It is wrong for Sen. Vitter to try to get something in return for moving forward on a matter that the Senate has considered routine for more than a century,” Majority Leader Harry Reid said in a statement. Democrats suggested Vitter was skating close to federal bribery laws that make it a crime to promise “anything of value … to influence any official act.”

Vitter’s not backing down.

“I’m glad the secretary has dropped his push for a pay raise,” Vitter said. “It was truly offensive to Gulf energy workers who are struggling under his policies. Now I hope he starts earning what he already makes and properly issues new permits for much needed drilling in the Gulf.”