Story highlights Republican defense hawks are proposing a $640 billion base budget for the Pentagon

The defense hawks argue Trump's budget was insufficient to rebuild the military

Washington (CNN) The House and Senate Armed Services Committees are planning to propose a defense budget of $640 billion for 2018, a $37 billion increase over the Trump administration's $603 billion request.

House Armed Services chairman Mac Thornberry told reporters Thursday he plans to set the topline of the House's annual defense authorization bill to $640 billion, along with a $65 billion war budget. And Senate Armed Services Committee chairman John McCain also plans to set his committee's bill at $640 billion, two sources familiar with his plans told CNN.

The increase for the defense authorization bill -- a must-pass piece of legislation that sets Pentagon policy and authorizes spending levels -- underscores the frustration of defense hawks like McCain and Thornberry with President Donald Trump's defense budget after he promised a massive rebuilding of the military.

The armed services chairmen have both been critical of the Trump budget request, which was $52 billion above the budget caps but only $18 billion more than what the Obama administration had proposed for 2018.

"What came up here at $603 billion was the Obama request, plus 3%," Thornberry said. "It's the Obama budget request because there wasn't anybody at DoD to write a Trump budget request."

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