As the presidential candidates face off in the Iowa Caucuses and the early primary states, a proxy war in under way over the Iran nuclear deal and the control of Congress.

The battle is taking place in fundraising emails between the Republican Jewish Coalition and J Street, a liberal pro-peace group, in an attempt to mobilize support for their respective efforts on a local level in 2016.

The first email came last week from the RJC responding to an announcement by J Street that they have raised more than $1 million to go on the offensive in Senate races in Illinois (incumbent Mark Kirk) and Wisconsin (incumbent Ron Johnson), attacking the senators who signed Sen. Tom Cotton’s letter to the Iranian ayatollahs back in March.

“The far left, anti-Israel supporters of J Street are already taking aim at our GOP allies in Congress who stood with us and opposed the Iran deal,” Matt Brooks, RJC’s Executive Director, stated in an email to supporters. “We need your help to protect our majorities in the House and Senate and provide cover to the Republican candidates who are under attack from J Street.”

The email urges supporters to help “Knock-Out J Street” by donating $25-$1000, reminding them that it was J Street “who cheered on the Obama Administration’s boycott of Netanyahu’s address to Congress last year. It was J Street that pushed through a dangerous nuclear deal that only empowers the mullahs in Iran. And now it is J Street who wants to defeat those that stood with Israel.”

On Friday, J Street’s Jeremy Ben-Ami countered the RJC mailer with an email attacking the RJC for calling them anti-Israel.

Referring to them as the “Sheldon Adelson group,” Ben-Ami wrote that “To the RJC, victory means intimidating American Jews who support Israel but oppose Netanyahu’s policies into silence.”

According to J Street, the RJC wants to “knock out” those who dared “to speak out when Netanyahu visits Congress to undermine the foreign policy of President Obama” and those who “dare to oppose the unrelenting expansion of settlements undermining Israel’s long-term security, democracy and Jewish character.”

“Will we be KO’d? No way. With your help, we’re only getting stronger,” the email concludes.

Without delay, as the sun rose on the west coast, the RJC sent out another email with the subject line “J Street responded…”

“First: We urged our supporters to defend pro-Israel candidates against the onslaught from J Street. Then: The George Soros-funded, anti-Israel, lobbying group responded with a vicious attack against us. Now: We need you to step up and defend Jewish Republicans by donating $20 right now,” the email reads.

Speaking to Jewish Insider, RJC’s Brooks said his group will do what they’ve done in the past, and that is “combat J Street race for race, and continue to beat them back in their efforts to defeat mainstream pro-Israel candidates.”

While J Street has said its goal is to raise at least $3 million in over 100 local races across the country, the RJC has yet to set such a goal. “Whatever it takes,” said Brooks. “We are going to make it very clear that J Street is not going to get a foothold by electing their progressive, left-wing and radical candidates, and trying to defeat mainstream pro-Israel folks, who’ve demonstrated their unwavering friendship over the years. We are making it very clear that there is a red line, and the RJC is defending that red line.”

J Street’s national political director, Ben Shnider countered the notion, saying the group has decided to seize the opportunity to expand its control and influence within the Democratic Party after scoring a victory on the Iran deal. “We see this as a unique opportunity to go on the offense and prove that standing up for a diplomacy first approach – which has been proven to be in the best interest of the U.S. and Israel – is not just smart policy but also savvy politics,” Shnider told Jewish Insider. “Our emphasis is going to be, primarily, in the Senate races in Illinois and Wisconsin. Kirk and Johnson stood in the way of this deal, and we think they should have to answer to that oppositions to a very pragmatic, centrist electorate.”

“This is shaping up to be a national security election, the first since the invasion of Iraq. This is going to be at the fore of the conversation, politically,” he added.

Shnider also criticized the RJC for referring to J Street as being anti-Israel. “It is preposterous. Everything we do is centered around what we believe to be in Israel’s best interest and the best interest of the U.S.-Israel alliance,” he asserted. “We can have our disagreements over policy, but our motives should not be questioned.”

But according to Brooks, “By definition, they [J Street] are anti-Israel and on the other side of where Israel is on critical issues such as the Iran deal.”

The back and forth email pitches and counter-attacks may well continue into the fall, regardless of who is on top of the ballot. In any case, the street fight may well benefit both organizations if it means convincing people to let go of their money in favor of each group as they seek to make inroads in these election cycle.