Ukraine's Zelenskyy tells Congress: 'We are united ... the entire free world'

House Minority Leader Kevin McCarthy -- who has previously signaled his reluctance to further back Ukrainian aid as the country fends off a Russian invasion -- told ABC News he would attend the Ukrainian president's address to Congress this evening.

"Well, by going to the Zelenskyy speech, we'd be listening to it," he said in remarks to reporters.

"We'll meet with him privately," he added.

McCarthy oversees some conservative members of the House Republican caucus who have ardently opposed additional funding for Ukraine and has himself spoken out against providing a "blank check" for the county without an audit of how it's spending the billions in U.S. aid.

Before his remarks, it was unclear if McCarthy would attend.

–ABC News' Trish Turner

As they spoke at the White House, Zelenskyy presented Biden with an award given to a Ukrainian soldier. The soldier wanted the president to have it, Zelenskyy explained.

"He's very brave," Zelenskyy said of the soldier, who he said is a captain of an HIMARS battery -- an advanced rocket system sent by the U.S. "And he said, 'give it to a very brave president.'"

Biden then asked for the solider's name and if there was any way to contact him.

"Undeserved but much appreciated," Biden said, adding he would give the captain a challenge coin.

In front of a roaring fire inside the Oval Office and flanked by reporters, Zelenskyy thanked President Biden for the support of the United States, which Biden said now includes a Patriot missile defense system and precision bomb kits.

"Thank you so much. Mr. President. Great honor for me to be here, with your journalists. Thank you so much for the invitation," Zelenskyy said. "I really wanted to come earlier, Mr. President knows, but I couldn't do it because the situation was so difficult."

Zelenskyy thanked Biden for his "big support and leadership," as well as the "ordinary" American people for standing with Ukraine.

"Thanks from our ordinary people to your ordinary people -- Americans -- I really appreciate." Zelenskyy said. "Thank you so much."

Welcoming Zelenskyy back to the Oval Office, Biden said it was an honor to be meeting again amid the "brutal" war being waged by Russia's Vladimir Putin.

"Hard to believe 300 days we've going through this, and Putin has waged a brutal assault on the Ukraine's right to exist as a nation and the attack on innocent Ukrainian people for no reason other than to intimidate," Biden said.

"And he's escalated his assault on civilians after hitting schools, orphanages, hospitals, landmarks, it's just -- and he's trying to use winter as a weapon. But the Ukrainian people continue to inspire the world. I mean that sincerely, not just inspire us but inspire the world with their courage and how they have chose resilience and resolve for their future," Biden said.

Biden said Democrats and Republicans will make sure Ukraine has the economic, humanitarian and security assistance they need to keep fighting and will "support Ukraine in pursuing a just peace."

"President Zelenskyy, the United States stands with the brave people of Ukraine, we stand with you, you've been a great leader," he said as he turned it over to Zelenskyy to give remarks.