More than a thousand pro-Israel supporters from across the country bombarded the offices of Senate Whip Dick Durbin (Ill.) with phone calls, urging the Democratic leader to stop holding up a key congressional initiative to rebuke the United Nations following its recent action against Israel, according to sources familiar with the situation.

Durbin's offices in Washington, D.C., and Chicago were so overwhelmed by phone calls that staffers were forced to take the phones off the hook for a short time, sources told the Washington Free Beacon.

The phone assault, led by the Republican Jewish Coalition, or RJC, is part of an effort to convince Durbin to release his hold on a Senate measure aiming to condemn the U.N. for its Obama administration-orchestrated efforts to chastise the Jewish state, a move that drew bipartisan outrage among lawmakers.

While the House of Representative already voted to overwhelmingly approve a similar measure, the Senate has balked, mainly due to opposition by Durbin and other Democratic leaders. The Senate resolution has the backing of 78 lawmakers, including Democrats.

The RJC launched the effort on Wednesday afternoon in an email urging its supporters across the country to call Durbin and insist he allow the pro-Israel measure to move forward.

Durbin's offices received more than 1,000 calls in about four hours. Supporters have continued making calls into Thursday, according to a source familiar with the effort.

The Senate resolution "is a bipartisan rebuke of the anti-Israel U.N. Security Council (UNSC) resolution that passed last month," the RJC wrote in its initial petition to supporters. "The U.N. [Security Council] targeted and isolated Israel, going so far as to declare Jerusalem, including the Western Wall, ‘occupied' territory."

"Most Americans were infuriated by this attack on Israel—and by the betrayal of the lame-duck Obama administration, which colluded with Israel's enemies to help the resolution pass," the RJC wrote.

The Free Beacon first disclosed late last year that the Obama administration played a key role in crafting the resolution and ensuring it passed. This included a call by former Vice President Joe Biden to the president of Ukraine insisting his country vote in favor of the anti-Israel action.

Fred Brown, a RJC spokesman, said the effort speaks to the wide support for Israel among the American public and highlights their desire for Congress to follow suit and condemn the U.N.

"In the face of an overwhelming desire to stand with Israel against the disgraceful actions of the United Nations and the Obama administration, Senator Durbin has chosen to play politics with the security of our closest ally, Israel," Brown said. "The American people made it clear last November that they are tired of these partisan games, and despite the senator's best efforts, they will not be ignored."

One source familiar with the phone offensive said that RJC supporters placed calls to Durbin's Whip office, as well as his local office in Illinois. Calls reached such a high volume that the phones in these offices were temporarily disabled, the source said.

"They turned on the automatic answering machine for a period and turned them back on after a bit," the source said. "They also did that at the constituent offices for a period."

Spokesmen for Durbin in his Whip office and congressional office did not respond to multiple requests for comment on the matter.