Helping Israel defend itself from rocket attacks by Palestinian militant group Hamas has proven to be one of the very few subjects capable of uniting Democrat and Republican lawmakers in the United States.

Congressmen and women from both political parties have rushed to seal a $225m (£133m) boost to Israel's Iron Dome missile defence system before breaking for a month-long summer recess.

The payment from the Defence Department to Israel had been discussed in Congress over the last week, whose members are responsible for legislating in the States. Republicans and Democrats have clashed over whether to approve the funds in a larger spending bill or separately, though no one publicly opposes the payments.

No money for Israel will be included in a larger House spending bill focused on border security, Representative Hal Rogers, the Appropriations Committee's Republican chairman has maintained.

He said military support for Israel would be addressed separately, though not necessarily soon – meaning the payment could go unapproved until September.

The Republican-led Congress is at odds with the Democratic-controlled Senate, which wants the Iron Dome money approved in a single package before lawmakers take their month break.

John Boehner, House of Representatives Speaker, said: "At times like this, people will try to isolate Israel. We are here to stand with Israel, not just as a broker or observer but as a strong partner and a trusted ally.

"What does that mean? Well, it doesn't mean issuing vague on-the-one-hand, on-the-other-hand statements. No, it means backing up our words and showing solidarity with our friend."

Israel has escalated its operation against Hamas as the conflict enters its fourth week. Israeli prime minister Benjamin Netanyahu warned of a "prolonged" campaign. Violence as a result of the Israeli Operation Protective Edge has seen the death of more than 1,100 Palestinians, mostly civilians, and more than 50 Israeli soldiers and three civilians.

Amid a daily barrage of rocket fire by Hamas from Palestine, Iron Dome has been credited with knocking hundreds of missiles out of the sky.

Even as President Barack Obama called for an "immediate, unconditional, humanitarian cease-fire", the Obama administration has backed Israel's request to replenish its missile defence stockpiles.