Pro-Ukraine demonstrators outside the White House demanded that President Biden “stand up” to his Russian counterpart Vladimir Putin in his first State of the Union address.

The group of about 50 protesters — many of them waving Ukraine flags — called on Biden to announce stricter sanctions against Moscow during his speech in the House chamber, which is set to start at 9 p.m.

“Ukrainians would rather die free than spend the rest of their lives in Putin’s gulag, but they need Biden’s help,” said Ilona Doerfler, who was draped in the yellow and blue flag.

The Ukrainian-born American, 47, said the measures announced by Biden, which take aim at Russian banks and oligarchs, aren’t severe enough to thwart the Kremlin invasion.

“We will know the sanctions are strong enough when Putin and his cronies stop bombing innocent Ukrainian civilians in their homes, schools and hospitals,” Doerfler told The Post.

The demonstration came as Russian forces stepped up their brutal attack on Ukraine’s population Tuesday, bombarding the central square in Kharkiv, Ukraine’s second-largest city, as well as Kyiv’s main TV tower.

The protesters want Biden to remove every Russian bank from the SWIFT international payment system, to better arm Ukrainian troops and to help enforce no-fly zones above the war-torn country.

“Putin’s forces can’t succeed on the ground against the will of the Ukrainian people, but Russian missiles have the advantage,” Doerfler said. 

“President Biden: close Ukrainian skies.”

US-born Israeli protester Catherine Pederssen, 31, urged Biden to censure Putin in the strongest terms during his address to Congress. 

“I’m here to show President Biden we support stronger measures to protect Ukraine,” Pederssen said. 

“Putin’s invasion of Ukraine is a threat to democracy worldwide.”

The demonstrators, some armed with megaphones, broke into chants of “Stand up to Putin,” “Putin is a war criminal” and “Ukraine needs more ammunition.”

“President Biden, do more for Ukraine,” they implored.

Some of the activists have been gathered on Pennsylvania Avenue, directly in front of the White House, since Thursday, but the group on Tuesday turned its attention to the State of the Union.

Biden is planning to say that Putin will “pay a price” for the invasion during his address, while highlighting the unified response of the West to Russian aggression.

“He rejected efforts at diplomacy. He thought the West and NATO wouldn’t respond. And, he thought he could divide us here at home,” Biden will say about Putin, according to excerpts of his speech released by the White House.

“Putin was wrong. We were ready.”