President Joe Biden on Tuesday mounted a full-throated case for maintaining critical support for Ukraine in its war with Russia — but sounded less certain than ever he’d be able to deliver on it.

Standing alongside Ukrainian President Volodymyr Zelenskyy, Biden hailed the nation’s survival during two years of brutal war as an “enormous victory.” He expressed full confidence that Ukraine could ultimately prevail, and vowed that his White House would remain steadfast in its allyship.

Yet facing entrenched Republican resistance to billions of dollars more in funding to strengthen Ukraine’s defenses, Biden could not deliver Zelensky what he wanted: a rock-solid promise.

“We’re in negotiations to get funding we need. Not making promises, but hopeful we can get there — I think we can,” Biden said at a White House press conference with Zelenskyy.

Minutes earlier, Biden said the U.S. would continue to supply Ukraine with air defenses, artillery and other weapons “as long as we can” — a far cry from the yearslong refrain that Washington would stand side by side with Kyiv for