Jerusalem — Israel's center-left opposition leader Isaac Herzog will travel to Washington to discuss his country's concerns over the Iranian nuclear deal, a spokesman said Wednesday, in the first sign of Israeli diplomatic action in response to the agreement.

There is widespread objection in Israel to the deal, and it dealt a heavy blow to Prime Minister Benjamin Netanyahu who spent years trying to prevent it.

"We must enter dialogue with our big ally, the U.S.," Herzog said in parliament Wednesday.

His spokesman, Ofer Newman, told The Associated Press that in Washington, Herzog will "explain what the problem is with the agreement" and discuss its security implications. Newman didn't elaborate on the timing of Herzog's trip or with whom he would meet, but stressed that he would not try to persuade U.S. lawmakers to block the deal.

Netanyahu's coalition partners and opposition leaders angrily criticized Tuesday's agreement, saying it will give Iran the capability to achieve nuclear weapons. Israeli leaders say a nuclear Iran is an existential threat to Israel because Iranian leaders have called for Israel's destruction.

Opposition leader Herzog — a main Netanyahu rival — has blamed the prime minister for the deal, saying Netanyahu had unnecessarily antagonized the U.S. and other allies. In March, Netanyahu voiced his opposition to the emerging deal in a speech to the U.S. Congress that enraged the White House.

But in a meeting with Netanyahu late Tuesday, Herzog enlisted "to do everything for the security of Israel" in light of the Iranian deal, according to a statement from Netanyahu's office.

"You can do all of this even from the opposition," Herzog said Wednesday in parliament, responding to criticism as to why he, an opposition figure, was going to Washington.

"Our national security is not a matter of dispute," he added.

Netanyahu called on Israeli opposition lawmakers to put their political differences aside and stand united on Israel's opposition to the deal.

"This is what is needed for Israel at this time. This is what the public expects of us," Netanyahu said.