By Mike Stone, Patricia Zengerle and Phil Stewart

WASHINGTON (Reuters) -The United States plans to announce more than $8 billion worth of military assistance for Ukraine on Thursday during Ukrainian President Volodymyr Zelenskiy’s visit to Washington, two U.S. officials said on Wednesday.

President Joe Biden’s administration has been engaged in urgent discussions with Congress to allow it to use up $5.6 billion in military aid for Ukraine before Sept. 30 – the end of the federal fiscal year – when the authority was set to expire.

On Thursday, U.S. officials said, the White House intends to notify Congress it will move forward with the announcement of a $5.6 billion drawdown from U.S. weapons stocks. The contents of that package are still in flux, the officials said.

Reuters reported this month that the Biden administration was considering a backup plan under which it would announce plans for shipments for Ukraine, but with an extended delivery timeline for the weapons and equipment, allowing for a more gradual transfer of resources to Ukraine without missing the Sept. 30 deadline.

A second announcement slated for Thursday will be for $2.4 billion worth of aid under the Ukraine Security Assistance Initiative program, which allows the administration to buy weapons for Ukraine from companies rather than pull them from U.S. stocks.

That aid will include munitions, weapons to combat drones and material to support munitions production in Ukraine, one of the U.S. officials said.

In addition, the U.S. plans – later on Wednesday – to announce $375 million worth of Presidential Drawdown Authority for Ukraine that will include the first shipment of a precision-guided glide bomb with a range of up to 81 miles (130 km) called the Joint Standoff Weapon, two U.S. officials said. The inclusion of that weapon was not expected to be publicly disclosed.

That package, which Reuters first reported on last week, was also expected to include patrol boats, additional ammunition for high-mobility artillery rocket systems (HIMARS), 155mm and 105mm artillery ammunition, spare parts and other weapons, U.S. officials said.

The Joint Standoff Weapon would be dropped from fighter jets, and is capable of striking targets with high accuracy. Ukraine has been largely prohibited from using U.S.-supplied weapons in strikes into Russia.

Presidential Drawdown Authority allows the president to draw from current weapons stocks to help allies in an emergency. In August, as Ukraine was pressing an incursion into Russia and losing territory in its east to Russian advances, Washington announced two packages, both for $125 million each.

Congress has approved nearly $175 billion of aid and military assistance for Ukraine and allied nations in the 2-1/2 years since Russia’s full-scale invasion, and many lawmakers say they expect Washington will need to approve more money to help the government in Kyiv in the next several months.

U.S. companies that might benefit from increased weapons shipments to Ukraine include arms makers like RTX, Lockheed Martin, General Dynamics, and Northrop Grumman.

(Reporting by Mike Stone, Patricia Zengerle and Phil Stewart in Washington; Editing by Jonathan Oatis)