Ukraine-Russia War: Live Updates and Latest News

Horrified by the images of death and destruction, Republicans and Democrats on Capitol Hill have needed little in the way of nudging to support the Ukrainian cause. In several cases, they have pressed the White House to take a more aggressive stance against Moscow in support of Kyiv, including increasing the size of a military and humanitarian aid package and endorsing the prohibition of Russian oil and gas imports.

Mr. Zelensky himself has been singularly successful at inspiring lawmakers to ratchet up aid.

Ukrainian officials plan to present the United States with a list of military equipment they need, including armed drones and mobile air-defense systems, according to European diplomats briefed on the request. Many Democrats and Republicans in Congress have signaled that they would be inclined to support such moves.

Congress last week approved $13.6 billion in military and humanitarian assistance to Ukraine, sending $6.5 billion to the Pentagon to cover the costs, which include deploying American troops to NATO countries on their Eastern border and providing Ukrainian forces with intelligence support. It also provided the funds to backfill weapons that the United States has already sent to the government in Kyiv.

On Tuesday night, the Senate unanimously approved a bill led by Senator Lindsey Graham, Republican of South Carolina, condemning President Vladimir V. Putin and Russian forces for “committing flagrant acts of aggression and other atrocities rising to the level of crimes against humanity and war crimes” in Ukraine. The legislation encourages the International Criminal Court to investigate those alleged war crimes.

Lawmakers have said they believe the Biden administration should send more arms. Legislation to send additional weapons to Kyiv, such as bigger mobile air-defense systems, would likely receive strong bipartisan votes in both chambers.

Mr. Zelensky has asked for Russian-made MIG fighter jets, although members of both parties have questioned such a move since the Defense Department raised concerns about whether Ukraine could even fly the planes.

Mr. Zelensky has also asked the United States to help close the airspace over his country to Russian aircraft. But Senator Mitch McConnell of Kentucky, the Republican leader, told reporters on Tuesday that Mr. Zelensky was unlikely to get congressional support for that. He also signaled ambivalence on the fighter jet transfer.

“Exactly how to make that happen is still under discussion,” Mr. McConnell said.

Democrats, who control Congress, have reiterated the importance of continuing to send humanitarian aid to Ukraine, and Speaker Nancy Pelosi, Democrat of California, said last week after speaking with Mr. Zelensky that lawmakers would eventually need to allocate funds to rebuild cities decimated by Russian bombing.

They have also shown few, if any, qualms about increasing military spending in response to the war.

Julian E. Barnes contributed reporting.