A US plan to provide nearly $40 billion in additional military and economic aid to Ukraine amid its conflict with Russia has hit a speed bump, with Senator Rand Paul (R-Kentucky) blocking a quick vote to approve the funding bill and likely delaying passage to at least next week.

Paul stood in the way on Thursday by objecting to a request by Senate leaders to approve "unanimous consent," a provision that allows bills with strong bipartisan support to be fast-tracked without debate. The former presidential candidate said he would only allow for a quick vote if the bill was revised to include the appointment of a special inspector general to monitor how the massive aid package is spent – a demand that Senate Majority Leader Chuck Schumer (D-New York) refused to meet.

Schumer claimed that Washington had a "moral obligation" to help Ukraine in its fight against Russian President Vladimir Putin's "immoral war." He said Paul's oversight provision was strongly opposed by Democrats and Republicans alike.