The Biden administration has told key lawmakers it is sending a new package of more than $1 billion in arms and ammunition to Israel, three congressional aides said Tuesday.

It's the first arms shipment to Israel to be announced by the administration since it put another arms transfer — consisting of 3,500 bombs — on hold this month. The administration has said it paused that earlier transfer to keep Israel from using the bombs in its growing offensive in the crowded southern Gaza city of Rafah.

The White House has come under criticism from both sides of the political spectrum in the U.S. over its military support for Israel's now seven-month war against Hamas in Gaza. Some of President Joe Biden's fellow Democrats have pushed him to limit transfers of offensive weapons to Israel to pressure the U.S. ally to do more to protect Palestinian civilians. Many Republicans condemn any lessening of military backing to Israel.

The package being sent includes about $700 million for tank ammunition, $500 million in tactical vehicles and $60 million in mortar rounds, the congressional aides said. They spoke on condition of anonymity to discuss an arms transfer that has not yet been made public.

There was no immediate indication when the arms would be sent. It's not clear if this shipment is part of the long-delayed foreign aid package that Congress passed and Biden signed last month, a tranche from existing arms sale or a new sale.

The Wall Street Journal first reported the plans to move the package.

House Republicans were planning this week to advance a bill to mandate the delivery of offensive weaponry for Israel. Following Biden's move to put a pause on bomb shipments last week, Republicans have been swift in their condemnation, arguing it represents the abandonment of the closest U.S. ally in the Middle East.

The White House said Tuesday that Biden would veto the bill if it were to pass Congress. The bill also has practically no chance in the Democratic-controlled Senate. But House Democrats are somewhat divided on the issue, and roughly two dozen have signed onto a letter to the Biden administration saying they were "deeply concerned about the message" sent by pausing the bomb shipment.

In addition to the written veto threat, the White House has been in touch with various lawmakers and congressional aides about the legislation, according to an administration official.

"We strongly, strongly oppose attempts to constrain the President's ability to deploy U.S. security assistance consistent with U.S. foreign policy and national security objectives," White House press secretary Karine Jean-Pierre said this week, adding that the administration plans to spend "every last cent" appropriated by Congress in the national security supplemental package that was signed into law by Biden last month.