WASHINGTON -- U.S. Sen. Chris Murphy joined 18 other members of the Senate Foreign Relations Committee in a bipartisan vote Tuesday approving legislation that gives Congress a limited say in the Iran nuclear deal.

Murphy, D-Conn., called the measure, hashed out between committee chairman Sen. Bob Corker, R-Tenn., and ranking Democrat Sen. Ben Cardin, D-Md., "incredibly productive.''

But he characterized the long back-and-forth that senators in both parties undertook to reach the agreement an "unnecessary endeavor.''

"The legislation we're debating today doesn't preserve for Congress any power that we don't already have,'' said Murphy, who unlike his Connecticut colleague, U.S. Sen. Richard Blumenthal, declined to support the Corker bill in its initial form.

But the negotiations to water down the original to make it more palatable to the White House "essentially make this legislation benign," Murphy said.

Murphy, a strong supporter of the administration's reaching an accord with Iran to limit that nation's capacity to build a nuclear weapon, had worried that the Republican-favored legislation would scuttle the delicate negotiations still necessary to reach a final agreement by the end of June.

The compromise bill approved Tuesday gives Congress a 30-day window before July 10 to review the final agreement. The original gave Congress 60 days.

It also watered down language linking the agreement to Iran halting support for terrorism.

In the 30-day period, Congress may hold hearings, receive classified briefings and documents, and ultimately vote whether to approve or reject it. President Barack Obama could lift sanctions imposed by the administration, but the vote could block the lifting of congressionally-imposed sanctions.

The prospect of Corker obtaining enough Democratic votes for a veto-proof majority prompted the White House to offer support Tuesday.

"With these changes ... this legislation, the passage of it, is not going to affect the negotiations,'' Murphy said. "So I'm happy to support it."

Blumenthal, who is not a member of the foreign relations committee, offered somewhat more enthusiastic support for the bill.

"I am pleased that the legislation that I co-sponsored has been adopted unanimously -- an affirmation by the Senate Foreign Relations Committee that the bill avoids any interference or impeding impact on ongoing negotiations to prevent a nuclear-armed Iran,'' he said in a statement. "I hope and believe that these negotiations can be successful, and offer the best prospect of achieving our common goal in stopping nuclear proliferation."