He said the US would give Israel ammunition to replenish the Iron Dome missile defence system and warned against other hostile actors joining the conflict.
“Let me say again, to any country, any organisation, anyone thinking of taking advantage of the situation, I have one word: don’t,” Mr Biden said in a press conference at the White House.
“This is not about party or politics, this is about the security of our world, the security of the United States of America.
“Let there be no doubt the United States has Israel’s back. We’ll make sure the Jewish and democratic state of Israel can defend itself today and tomorrow, as we always have.”
The president does not require the approval of Congress to use the US military, including the movement of the USS Gerald R. Ford carrier group transferred to the Eastern Mediterranean on Sunday.
But he does require funding to replenish the US’s weapons stocks after a transfer has been made to another country.
John Kirby, the National Security Council’s coordinator for strategic communications, said on Monday: “Both [Israel and Ukraine] are important, and we are a large enough, big enough, economically viable and vibrant enough country to be able to support both.”
However, Republicans responded by suggesting that they would seek to separate measures on the two countries if they are introduced as one bill.
“I will not hold up funding for Israel if that becomes a vote problem,” one Republican told Politico. “Then I will support decoupling them.”
On Tuesday evening, Republican congressmen planned to meet to discuss who will replace Mr McCarthy as Speaker, in the hope of filling the vacancy before the end of the week.
Republican presidential candidates also sought to use the crisis to burnish their foreign policy credentials.
Donald Trump, the frontrunner, has promoted his record on Middle Eastern diplomacy and work on the Abraham Accords, Arab-Israeli normalisation agreements signed in 2020.
He posted on his Truth Social platform: “I KEPT ISRAEL SAFE! NOBODY ELSE WILL, NOBODY ELSE CAN, AND I KNOW ALL OF THE PLAYERS!!!”
Nikki Haley, who is currently polling third in the GOP race, has said she considers Israel the “front line of defence” for America and, following Hamas’s attack, called on Benjamin Netanyahu to “finish them”.