President Joe Biden will host Ukrainian President Volodymyr Zelensky at the White House Tuesday as discussions on a Ukraine aid deal remain stalled in Congress.

The visit, which the White House announced Sunday, is Zelensky’s third visit to Washington since the war in Ukraine began. He last visited in September.

Zelensky’s visit comes at a critical moment in congressional negotiations for emergency aid to Ukraine. Congress appears no closer to a deal tying immigration and border policy changes to the emergency aid package that will provide funding for Ukraine and Israel before lawmakers leave town for the holidays.

The Ukrainian president was also invited to speak at an all-senators meeting Tuesday morning by Majority Leader Chuck Schumer and Republican Leader Mitch McConnell, a Senate leadership aide said. House Speaker Mike Johnson will meet with Zelensky too, his office said in a statement.

The White House meeting is meant to “underscore the United States’ unshakeable commitment to supporting the people of Ukraine as they defend themselves against Russia’s brutal invasion,” press secretary Karine Jean-Pierre said in a statement.

“As Russia ramps up its missile and drone strikes against Ukraine, the leaders will discuss Ukraine’s urgent needs and the vital importance of the United States’ continued support at this critical moment,” she said.

The pair will discuss “further defense cooperation” in a series of meetings Tuesday, the office of the Ukrainian presidency said in a statement Sunday.

Zelensky will focus on “securing unity among the US, Europe, and the rest of the world” on their support of Ukraine’s defense against Russia and “strengthening the international order based on rules and respect for the sovereignty of nations,” the statement read.

Zelensky and Biden will also discuss defensive cooperation efforts for the coming year, including joint projects to produce weapons and air defense systems.

If Congress leaves town for the holidays without reaching a deal, the White House will have to make tough choices about supplying allies such as Ukraine at the potential expense of US military readiness. Top Biden administration officials have been sounding the alarm for weeks about funding for Ukraine running dry and the potential consequences.

The administration’s proposed $106 billion aid package includes about $60 billion in aid toward Ukraine’s defenses against Russia, with the rest going toward Israel’s war with Hamas, security in Taiwan and funding for operations at the US-Mexico border.

But top Republicans, wary of adding more to the $111 billion the US has already sent to Ukraine, have asked that any further funding be tied to major immigration-related policy changes.

“History’s going to judge harshly those who turn their back on freedom’s cause,” Biden said earlier this month. “We can’t let Putin win.”