Biden to make prime-time case for US assistance to Israel and Ukraine

President Joe Biden will address the nation in prime time on Thursday, fresh off a wartime visit to Israel, a high-stakes test of his personal diplomacy and U.S. world leadership in a crisis.

Speaking from the Oval Office at 8 p.m. ET, Biden will make the case to Americans that it's vital to both global and U.S. national security to assist Israel as it responds to the terror attacks by Hamas, as well as to continue help for Ukraine as it fends off Russian invaders.

"What the president is going to be doing is laying out for the American people a description of this moment that we are in," deputy national security adviser Jonathan Finer said on ABC's "Good Morning America."

Biden will use the remarks to "connect that national moment to American lives back here," Finer said, and explain why the administration and lawmakers need to continue to show leadership.

He will talk about how painful recent events have been for millions of Americans.

In Tel Aviv, Biden pledged unwavering support to Israel but also successfully made the case to Prime Minister Benjamin Netanyahu and his war cabinet to allow humanitarian aid to enter Gaza. Taking reporter questions on the way home, Biden spoke to the political risk, including to himself, saying, "had we gone and this failed, then, you know the United States failed, Biden's presidency failed, et cetera, which would be legitimate criticism."

The national address comes as Biden's team prepares to send a large foreign aid package to Capitol Hill. The proposal, still in flux, could amount to $100 billion, including a whopping $60 billion more for Ukraine, sources familiar with the draft told ABC News.

The draft proposal would also include $10 billion for Israel, as well as money for the U.S.-Mexico border -- likely an appeal to conservatives who've expressed opposition to sending more assistance to Ukraine.

But the request will fall on a paralyzed Congress, with the House without a speaker since the historic ouster of Kevin McCarthy more than two weeks ago. Republicans have, so far, been unable to come to a consensus on a successor, leaving the chamber in chaos.

The terror attacks in Israel have prompted some sense of urgency to fill the void. Oklahoma Rep. Tom Cole, while nominating Ohio's Jim Jordan for the post, received a standing ovation from Republicans and Democrats alike when he invoked Israel's right to defend itself. But as of Thursday, the path forward to handing down the speaker's gavel remained unclear.

Biden on Wednesday told Israel they are "not alone" and that his administration would make sure leaders have "what you need to protect your people, to defend your nation."

But he also urged officials to practice caution, warning them not to repeat what he called the "mistakes" made by the United States in the aftermath of 9/11. He also issued a pointed reminder that Israel, as a democracy, has an obligation to the rules of law.

On his way back to Washington, Biden took a victory lap on securing some limited humanitarian aid to Gaza. Biden said Egypt would allow up to 20 trucks with aid to pass through the Rafah border crossing, which has been closed since the coNFLict began. The aid is also subject to conditions, including that it never reach Hamas.

"I came to get something done -- I got it done," he told reporters on Air Force One.

But he was vague on the prospect of securing a safe passage out for civilians who want to leave Gaza, and announced no updates on getting back U.S. hostages held by Hamas.

The trip, risky physically as well as politically, came eight months after he made a surprise visit to Kyiv to mark one year since Russia's invasion.

There, he said "unchecked aggression" demonstrated by Russia "is a threat to all of us."

"You remind us that freedom is priceless; it's worth fighting for for as long as it takes," Biden told Ukrainian President Volodymyr Zelenskyy at the time. " And that's how long we're going to be with you, Mr. President: for as long as it takes."

The Biden administration has been pressed on whether it can assist both Ukraine and Israel. Biden has assured the U.S. can.

Prior to his speech, Biden spoke with Zelenskyy, the White House confirmed.

Zelenskyy said he thanked the U.S. president for sending ATACMs, or long-range missiles, to help Ukraine's counteroffensive.

Zelenskyy also said he "welcomed" Biden's visit to Israel aimed "at seeking peace and protection of civilian lives" and that Ukraine was "grateful for the vital and enduring U.S. support in our fight for freedom."

ABC News' Mary Bruce, Anne Flaherty, Rachel Scott and Justin Gomez contributed to this report.