Debate is heating up ahead of a June 30 deadline to finalize a framework agreement that would give Iran sanctions relief in exchange for assurances against a nuclear weapon program.

Iran, under the terms of a November 2013 agreement meant to curtail nuclear advancements, is limited to exports of around 1 million barrels per day, about half of the country's full potential. The U.S. Treasury Department estimated Iran was out about $40 billion in revenue last year as a result of sanctions.

Murkowski, R-Alaska, chairwoman of the Senate Energy Committee, said crude oil prices would likely fall if more Iranian crude oil enters the market as a result of an easing of sanctions pressure.

"The net effect will be to negatively impact oil production in the United States," the report read. "Lifting sanctions against Iran without also lifting the ban on U.S. exports will allow Iran to compete in markets largely inaccessible to American companies."

The Iranian government in early May said representatives from the United States were among those expected to attend an international investment conference in Tehran. Washington countered that Iran was not yet open for business, though U.S. company Exxon Mobile disclosed it was monitoring developments in Iran closely.

Murkowski has moved several pieces of legislation aimed at ending a ban on U.S. crude oil exports. A moratorium was enacted in the 1970s after Arab members of the Organization of Petroleum Exporting Countries closed the tap in response to U.S. support for Israel.

With U.S. oil production eclipsing 9 million barrels per day, Murkowski argued earlier this month that ending the export ban would be a strategic initiative.

"This is something that is simply in the best interest of the United States, in terms of both our economic strength and our national security," she said in an earlier statement.

A report from the nonpartisan Congressional Research Service finds some overseas refineries aren't designed to handle the lighter oils from the United States.

Despite some oil leaving the domestic market under various circumstances, the White House has maintained there has been no change in export regulations.