Tucker Carlson said late Wednesday that his much-anticipated interview with President Vladimir V. Putin of Russia would be broadcast on Thursday night, even as a bill to send tens of billions of dollars to Ukraine remains hung up in Congress.

Mr. Carlson, the former Fox News host, made the announcement in an Instagram post, which said the interview would be broadcast on tuckercarlson.com at 6 p.m. Eastern time. It would be Mr. Putin’s first formal interview with a Western media figure since the start of his full-scale invasion of Ukraine, despite multiple requests from a variety of news outlets.

The interview was conducted on Tuesday, said a Kremlin spokesman, Dmitri S. Peskov.

Mr. Carlson has spent several days in Moscow, according to Russian state media, which has delivered a blow-by-blow account of his visit, raising anticipation of a potential interview. He confirmed on Tuesday night that there would be one.

“We’re here to interview the president of Russia, Vladimir Putin,” Mr. Carlson said in a video apparently shot from a high-rise building in central Moscow and posted to X, the social media platform. “We’ll be doing that soon.”

Mr. Putin’s government has drastically reduced the ability of Western journalists to cover Russia, and it has imprisoned a Wall Street Journal correspondent, Evan Gershkovich, for more than 10 months on espionage charges that he, his employer and the United States government vehemently deny. The Kremlin has referred to Western countries as having been “stupefied” by anti-Russian propaganda.

The interview comes at a critical time for the war in Ukraine, with American aid to Kyiv stalled in Congress. On Wednesday, the Senate adjourned without moving forward on an aid package for Ukraine and Israel, after Republicans blocked a compromise that would have paired the aid with stringent border security measures.