US Vice President Joe Biden
US Vice President Joe BidenIsrael news photo: Flash 90

U.S. Vice President Joe Biden briefed a dozen Democratic senators on Wednesday on the negotiations with Iran over its nuclear weapons program, reports The Hill.

"The Vice President underscored that the relief we would provide Iran as part of the first step would be modest and temporary compared to the substantial, continuing impact of our sanctions, which would be vigorously enforced throughout the first step," the White House said in a statement.

According to The Hill, the two-hour meeting included members of the vice president's national security team and some of the upper chamber's most dovish members.

Attendees included Sens. Richard Blumenthal (Conn.), Cory Booker (N.J.), Benjamin Cardin (Md.), Thomas Carper (Del.), Robert Casey (Pa.), Al Franken (Minn.), Tim Kaine (Va.), Joe Manchin (W.Va.), Jeff Merkley (Ore.), Chris Murphy (D-Conn.), Jeanne Shaheen (N.H.), and Elizabeth Warren (Mass.).

The meeting comes in the wake of a very aggressive campaign by the administration to convince senators to wait before approving harsher sanctions on Iran.

Several weeks ago, Biden joined other top officials from the Obama administration in a meeting with Senate Majority Leader Harry Reid (D-Nev.) and other senior Senate Democrats as the White House lobbies against additional punitive measures against Iran at this time.

On Tuesday, Obama himself met with lawmakers and told them that Iran would make progress in its ability to build a nuclear weapon if there is no diplomatic deal to halt or roll back its nuclear program.

Last week, Obama issued a public warning to Congress, saying that a deal in the works could prevent the "unintended consequences" of war.

The Senate Banking panel has been considering whether to act on legislation hitting Iran’s oil industry. The House overwhelmingly passed such legislation in July, but the White House has been urging Senate Democrats to hold off while multilateral talks on Iran’s nuclear program continue.

During a panel hosted by the Wall Street Journal on Wednesday, Obama said he had told lawmakers and Israel that it was important to test whether a diplomatic solution was possible.

"Let's test the proposition over the next six months we can resolve this in a diplomatic fashion while maintaining the essential sanctions architecture," Obama was quoted as having said.

The president said that under the proposed short-term deal, the Iranians would halt their nuclear weapons program, roll back certain elements, and subject themselves to "vigorous inspections."

Obama said the U.S. was offering a "very modest amount of relief that is entirely subject to reinstatement if in fact they violated any part of this earlier agreement."