(WASHINGTON) -- Vice President Kamala Harris on Thursday pledged to continue support to Ukraine as she met with President Volodymyr Zelenskyy to discuss his so-called "victory plan" to bring an end to war with Russia.
Harris cast the conflict as a fight for fundamental principles of "freedom and independence."
"We also know that other would-be aggressors around the world are watching to see what happens in Ukraine," Harris said. "If Putin is allowed to win, they will become emboldened, and history reminds us, and history is so clear in reminding us, the United States cannot and should not isolate ourselves from the rest of the world. Isolation is not insulation."
Harris also appeared to take a swipe at her political opponents -- former President Donald Trump and his running mate, Ohio Sen. JD Vance -- who've floated Ukraine ceding territory to Russia as part of negotiations to end the war.
"However, in candor, I share with you Mr. President, there are some in my country who would, instead, force Ukraine to give up large parts of its sovereign territory, who would demand that Ukraine accept neutrality and would require Ukraine to forego security relationships with other nations," Harris said.
"These proposals are the same of those of Putin. And let us be clear, they are not proposals for peace. Instead, they are proposals for surrender, which is dangerous and unacceptable," she added.
This is Zelenskyy's fifth visit to Washington since Russia's invasion began in Feb. 2022, and he now faces an increasingly partisan environment with an election just weeks away.
Trump ratcheted up his criticism of Zelenskyy and Ukraine on Wednesday, calling Zelenskyy the "greatest salesman on Earth" and painting a picture of an "obliterated Ukraine."
The former president also suggested Ukraine should've made a "deal" before the war started. Trump said, "If they made a bad deal it would’ve been much better. They would’ve given up a little bit and everybody would be living."
Trump also accused Zelenskyy of making "little, nasty aspersions" about him, likely referring to Zelenskyy's comments to The New Yorker casting doubt on Trump's claim he could quickly end the Russia-Ukraine war.
After sources saying Wednesday Trump was not expected to meet with Zelenskyy, Trump told reporters Thursday afternoon Zelenskyy had asked to meet and that they would do so Friday morning at Trump Tower.
"I believe I will be able to make a deal between President Putin and President Zelensky quite quickly," Trump said, but when asked what that would look like, he responded, "I don't want to tell you what that looks like."
And when asked to respond to respond to what a reporter said was Harris' suggestion that his strategy amounted to "surrender" to Russia, Trump said, "No, I don't think so. I don't think so. And, it's not a surrender. What my strategy is to save lives. I want to save lives. Millions of people are dead. Millions more than they even think about. And it's not my fight, but it is a fight to save humanity."
Zelenskyy has also called Vance "too radical," taking issue with his statements that a Trump-Vance administration's approach to the war would likely include Ukraine ceding territory to Russia and the current line of demarcation becoming a demilitarized zone. Vance said on Wednesday that "everything would be on the table" when asked if Ukraine should cede land.
The top Republican on Capitol Hill, House Speaker Mike Johnson, did not meet Zelenskyy when he visited Capitol Hill earlier Thursday to meet with a bipartisan group of House lawmakers. Johnson told reporters he would not be in town, but if he had sat down with Zelenskyy would have aired grievances about his tour of an American munitions manufacturing plant in Pennsylvania.
Zelenskyy made the case to lawmakers for permission to strike deeper into Russia at military targets using U.S.-supplied weapons. Several senators on both sides of the aisle expressed a desire for Biden to give Zelenskyy authorization to do so.
But the White House continued to express opposition to such a move.
White House press secretary Karine Jean-Pierre, peppered with questions on the issue during Thursday's briefing, told reporters not to "expect any new announcements" coming out of Zelenskyy's one-on-one meeting with Biden.
"Our policy has not changed," Jean-Pierre said. "They're going to talk on a range of issues today. What we can say and what we can commit to is that we will continue to support Ukraine as they continue their fight against Mr. Putin's aggression, into Ukraine. And so that is our commitment, that's what the president is focused on."
In the Oval Office, Biden said he looked forward to discussing Zelenskyy's "victory plan" and said he saw two key pieces in aiding Ukraine.
The first, Biden said, was to "strengthen Ukraine's position on the battlefield." He then highlighted the new $2.4 billion package of security systems announced earlier Thursday and his directive to the Pentagon to allocate all remaining security system funding by the end of his term.
The second, Biden said, was to "look ahead to help Ukraine succeed in the long term" by helping Ukraine join NATO and the European Union as well as reforms to counter corruption, strengthen democracy and enhance security in the nation.
"Let me be clear: Russia will not prevail in war. Russia will not prevail. Ukraine will prevail, and we'll continue to stand by you every step of the way," Biden said.
ABC News' Allison Pecorin, Lauren Peller, Michelle Stoddart and Cheyenne Haslett contributed to this report.