Reports revealed on Friday that a spokesperson for Vance's office confirmed the letter was authentic.
"What is our [US] strategy and what is the president’s exit plan? It would be an absurd abdication of congressional responsibility to grant this request without knowing the answers to these questions," the draft letter states.
"For these reasons, and others, we oppose the additional expenditure for the war in Ukraine, included in your supplemental request."
The letter is dated September 5 and it is unclear whether other lawmakers will cosign it as well.
The lawmakers, both Republicans, urge Biden in the letter to be much more transparent and clear about his strategy in Ukraine and how the significant US funds are being used in that country.
The US' continued aid to Ukraine has in recent months proven to be a major issue for many everyday Americans and lawmakers on Capitol Hill, who have repeatedly called out that funding should be redirected to focus on domestic matters. In fact, a poll published in early August revealed that the majority of surveyed Americans were entirely against authorizing additional funds for Ukraine.